US20050100471A1 - White gold alloy - Google Patents
White gold alloy Download PDFInfo
- Publication number
- US20050100471A1 US20050100471A1 US10/662,197 US66219703A US2005100471A1 US 20050100471 A1 US20050100471 A1 US 20050100471A1 US 66219703 A US66219703 A US 66219703A US 2005100471 A1 US2005100471 A1 US 2005100471A1
- Authority
- US
- United States
- Prior art keywords
- gold
- alloy
- cobalt
- nickel
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 40
- 239000000956 alloy Substances 0.000 title claims abstract description 40
- 229910000832 white gold Inorganic materials 0.000 title abstract description 19
- 239000010938 white gold Substances 0.000 title abstract description 14
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 40
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000010931 gold Substances 0.000 claims abstract description 22
- 229910052737 gold Inorganic materials 0.000 claims abstract description 22
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 20
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 18
- 239000010941 cobalt Substances 0.000 claims abstract description 18
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 18
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 16
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910052802 copper Inorganic materials 0.000 claims abstract description 16
- 239000010949 copper Substances 0.000 claims abstract description 16
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 15
- 239000011701 zinc Substances 0.000 claims abstract description 15
- 229910001020 Au alloy Inorganic materials 0.000 claims abstract description 14
- 239000003353 gold alloy Substances 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000005096 rolling process Methods 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 24
- 229910052763 palladium Inorganic materials 0.000 description 12
- 238000009472 formulation Methods 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 239000007844 bleaching agent Substances 0.000 description 5
- 229910001097 yellow gold Inorganic materials 0.000 description 5
- 239000010930 yellow gold Substances 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000009713 electroplating Methods 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052703 rhodium Inorganic materials 0.000 description 2
- 239000010948 rhodium Substances 0.000 description 2
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 229910001252 Pd alloy Inorganic materials 0.000 description 1
- 241001085205 Prenanthella exigua Species 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000001996 bearing alloy Substances 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- MSNOMDLPLDYDME-UHFFFAOYSA-N gold nickel Chemical compound [Ni].[Au] MSNOMDLPLDYDME-UHFFFAOYSA-N 0.000 description 1
- BBKFSSMUWOMYPI-UHFFFAOYSA-N gold palladium Chemical compound [Pd].[Au] BBKFSSMUWOMYPI-UHFFFAOYSA-N 0.000 description 1
- 238000010135 hand fabrication Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 230000003245 working effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C5/00—Alloys based on noble metals
- C22C5/02—Alloys based on gold
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
Definitions
- This invention relates to gold alloys and more particularly to a range of novel 22-karat white gold alloy formulations.
- White gold formulations possess a bright white platinum color. At a higher karat values, their metallurgical properties may be inferior to more common yellow gold alloys.
- White gold was developed as an alternative to platinum when the Russian Revolution disrupted production of that metal during World War I.
- White golds can be broadly classified into two categories: gold-palladium alloys and gold-nickel alloys.
- Palladium is added to gold (often with lesser amounts of silver, copper and zinc) to bleach the natural yellow color of pure gold to a gray-white color.
- gold alloys containing greater than 15% (w/w) palladium are considered to be “white”.
- 22K (91.67% gold) alloys can contain a maximum of 8.33% palladium, resulting in a 9% palladium formulation that suffers from an undesirable off-yellow color and is much too soft in both the annealed and work hardened states to be fabricated into the most primitive of jewelry products.
- Less than the maximum percentage of palladium in a 22K white gold formulation balanced with additions of silver, copper and zinc does little to improve the hardness and degrades an already poor color.
- Nickel-bearing white golds are more popular for jewelry fabrication than the palladium containing alloys largely due to their lower cost.
- nickel-bearing white golds of acceptable color are so much harder and brittle as compared to their yellow gold counterparts that many mechanical and hand fabrication techniques cannot be applied to these materials.
- nickel-bearing white gold alloys suffer from either from poor metallurgical properties or they have reasonable working properties with an off yellow color, or both.
- Electroplating finished yellow-tinged “white” gold jewelry with rhodium to whiten the finished jewelry not only increases fabrication and intrinsic metal costs but presents a wide variety of stone setting, sizing, repair, usage and general wear issues. For example, a finger ring that must be increased in size often must be cut then stretched and a gold insert soldered into newly created opening. Rhodium plated jewelry will often blister and crack during cutting, stretching and soldering. Even without cracking and blistering, all or part of the ring must be re-plated after the mechanical sizing operations to standardize the finish.
- white gold jewelry fabricated from either palladium or nickel bearing alloys may suffer from a variety of technical and/or financial problems.
- the weight percentage available for elements to bleach an increasing proportion of yellow gold and for other elemental additives decreases.
- a 22 karat white gold alloys has only 8.33% of the alloy weight available for (1) bleaching the yellow gold color from 91.67% of the weight to an acceptable gray/white color and (2) developing alloy metallurgical characteristics consistent with standard jewelry manufacturing techniques while maintaining a cost competitive formulation.
- the resulting alloy has the following composition: gold 90.9-93.0% copper 0.4-0.8% nickel 6.0-7.5% cobalt 0.02-0.50% zinc 0.50-1.0% More preferably, these elements are present in the following ranges: Gold ⁇ 91.67%; Zinc 0.5 to 1.0%; Nickel 6.0 to 7.5%; Copper 0.4 to 0.8%; Cobalt 0.02 to 0.10%. Typically cobalt is present at least as 0.03% by weight.
- the above-described alloy can be produced using a master alloy and mixing the master alloy with gold in approximately a weight ratio that provides 90.9-93% gold (nominally 91.67% or 22 kt) with the remaining amount being the master alloy.
- the master alloy composition is (by weight): nickel 72-90%; zink 4.8-18.0% (preferably 6.0-12.0%) copper 4.8-18.0% (preferably 0.24-1.2%); and cobalt 0.24 to 1.2% (typically cobalt is present at least as 0.4% by weight).
- the invention also features methods of making jewelry having the above formulation.
- An example of the new alloys according to my invention has the following composition in weight percent: Gold 91.67% Zinc 0.66% Nickel 7.00% Copper 0.60% Cobalt 0.07% Total 100.00%
- Bars, rods and finished jewelry products of the above composition have a pleasing white color similar to platinum jewelry alloys without visible yellow discoloration. Palladium electroplating of the finished pieces generally is not necessary to improve the color.
- Sheet can be rolled to thicknesses usual to jewelry stamping operations and stamped into two and three-dimensional parts. Such parts can be threaded or formed into springs using fabrication equipment and process common to lower karat yellow and white golds.
- Wire made from the same composition can be drawn to diameters typically used for earring posts and chain production without the usual breaking and complicated annealing processes normally required for lower karat white golds.
- a pre-alloy (“master alloy”) may be used.
- An example of the master alloy for the new 22 k white gold composition in weight percent is: Zinc 7.92% Nickel 84.03% Copper 7.21% Cobalt 0.84% Total 100.00%
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Adornments (AREA)
Abstract
By including zinc, nickel, copper and cobalt in a 22 kt gold alloy, it is possible to obtain the desired white gold color in an alloy with satisfactory metallurgical properties and with reasonable raw material costs. More specifically, these elements are present in the following ranges: Gold≈91.67%; Zinc 0.4 to 1.5%; Nickel 6.0 to 7.5%; Copper 0.4 to 1.5%; Cobalt 0.02 to 0.50%. Master alloys and methods of making jewelry are also disclosed.
Description
- Under 35 USC §119(e)(1), this application claims the benefit of prior U.S. provisional application 60/410,671, filed Sep. 13, 2003, which is hereby incorporated by reference in its entirety.
- This invention relates to gold alloys and more particularly to a range of novel 22-karat white gold alloy formulations.
- White gold formulations possess a bright white platinum color. At a higher karat values, their metallurgical properties may be inferior to more common yellow gold alloys.
- White gold was developed as an alternative to platinum when the Russian Revolution disrupted production of that metal during World War I. White golds can be broadly classified into two categories: gold-palladium alloys and gold-nickel alloys.
- Palladium is added to gold (often with lesser amounts of silver, copper and zinc) to bleach the natural yellow color of pure gold to a gray-white color. A generally accepted rule is that gold alloys containing greater than 15% (w/w) palladium are considered to be “white”. 22K (91.67% gold) alloys can contain a maximum of 8.33% palladium, resulting in a 9% palladium formulation that suffers from an undesirable off-yellow color and is much too soft in both the annealed and work hardened states to be fabricated into the most primitive of jewelry products. Less than the maximum percentage of palladium in a 22K white gold formulation balanced with additions of silver, copper and zinc does little to improve the hardness and degrades an already poor color.
- In addition to technical issues with relatively high levels of palladium, financial considerations compound the manufacturing problems. In recent years the unit cost of pure palladium has often greatly exceeded that of pure gold. Under these financial circumstances, a 22K (or even lower karat white gold alloys) containing a significant proportion of palladium as a bleaching agent will often exceed the intrinsic value of the same item in pure gold. This increased in cost over the marked karat quality is without readily apparent benefit and may be unacceptable to jewelry manufacturers and consumers alike.
- As with palladium, nickel is added to white gold formulations to bleach the natural yellow color of pure gold. Nickel-bearing white golds are more popular for jewelry fabrication than the palladium containing alloys largely due to their lower cost. Unfortunately, when nickel is used in gold alloys in a sufficient weight percentage to bleach the yellow to the target gray/white color, the undesirable side effects of much greater hardness and a marked reduction in ductility may occur in both the work hardened and fully annealed states. Nickel-bearing white golds of acceptable color are so much harder and brittle as compared to their yellow gold counterparts that many mechanical and hand fabrication techniques cannot be applied to these materials. In general, nickel-bearing white gold alloys suffer from either from poor metallurgical properties or they have reasonable working properties with an off yellow color, or both.
- In some cases poor color may be offset by electroplating the finished product. Electroplating finished yellow-tinged “white” gold jewelry with rhodium to whiten the finished jewelry not only increases fabrication and intrinsic metal costs but presents a wide variety of stone setting, sizing, repair, usage and general wear issues. For example, a finger ring that must be increased in size often must be cut then stretched and a gold insert soldered into newly created opening. Rhodium plated jewelry will often blister and crack during cutting, stretching and soldering. Even without cracking and blistering, all or part of the ring must be re-plated after the mechanical sizing operations to standardize the finish.
- In summary, white gold jewelry fabricated from either palladium or nickel bearing alloys may suffer from a variety of technical and/or financial problems. Furthermore, as the gold karat quality increases, the weight percentage available for elements to bleach an increasing proportion of yellow gold and for other elemental additives decreases. For example, a 22 karat white gold alloys has only 8.33% of the alloy weight available for (1) bleaching the yellow gold color from 91.67% of the weight to an acceptable gray/white color and (2) developing alloy metallurgical characteristics consistent with standard jewelry manufacturing techniques while maintaining a cost competitive formulation.
- By including zinc, nickel, copper and cobalt in a 22 kt gold alloy, it is possible to obtain the desired white gold color in an alloy with satisfactory metallurgical properties and with reasonable raw material costs. In general the resulting alloy has the following composition:
gold 90.9-93.0% copper 0.4-0.8% nickel 6.0-7.5% cobalt 0.02-0.50% zinc 0.50-1.0%
More preferably, these elements are present in the following ranges: Gold≈91.67%; Zinc 0.5 to 1.0%; Nickel 6.0 to 7.5%; Copper 0.4 to 0.8%; Cobalt 0.02 to 0.10%. Typically cobalt is present at least as 0.03% by weight. - The above-described alloy can be produced using a master alloy and mixing the master alloy with gold in approximately a weight ratio that provides 90.9-93% gold (nominally 91.67% or 22 kt) with the remaining amount being the master alloy. The master alloy composition is (by weight):
nickel 72-90%; zink 4.8-18.0% (preferably 6.0-12.0%) copper 4.8-18.0% (preferably 0.24-1.2%); and cobalt 0.24 to 1.2% (typically cobalt is present at least as 0.4% by weight). - The invention also features methods of making jewelry having the above formulation.
- The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
- An example of the new alloys according to my invention has the following composition in weight percent:
Gold 91.67% Zinc 0.66% Nickel 7.00% Copper 0.60% Cobalt 0.07% Total 100.00% - Bars, rods and finished jewelry products of the above composition have a pleasing white color similar to platinum jewelry alloys without visible yellow discoloration. Palladium electroplating of the finished pieces generally is not necessary to improve the color.
- Bars cast from the above composition roll without cracking or intermediate annealing to 50% of the original thickness. After annealing at about 1425° F. for 15 minutes, the 50% reduced plates can again be reduced 50% in thickness without cracking or other problems.
- Sheet can be rolled to thicknesses usual to jewelry stamping operations and stamped into two and three-dimensional parts. Such parts can be threaded or formed into springs using fabrication equipment and process common to lower karat yellow and white golds.
- Wire made from the same composition can be drawn to diameters typically used for earring posts and chain production without the usual breaking and complicated annealing processes normally required for lower karat white golds.
- In order to more easily prepare a uniform 22 k white gold composition, a pre-alloy (“master alloy”) may be used. An example of the master alloy for the new 22 k white gold composition in weight percent is:
Zinc 7.92% Nickel 84.03% Copper 7.21% Cobalt 0.84% Total 100.00% - To prepare the new 22 k white formulation from the master alloy and fine gold 8.33 weight parts of master alloy would be melted with 91.67 weight parts fine gold.
- A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.
Claims (19)
1. A gold alloy comprising by weight about 90.9-93.0% gold and:
0.4 to 1.5% zinc;
6.0 to 7.5% nickel;
0.4 to 1.5% copper; and
0.02 to 0.50% cobalt.
2. The gold alloy of claim 1 comprising by weight:
0.5 to 1.0% zinc;
6.0 to 7.5% nickel;
0.4 to 0.8% copper; and
0.02 to 0.10% cobalt.
3. The gold alloy of claim 2 in which the cobalt is present in about 0.03 to 0.10% by weight.
4. The gold alloy of claim 1 in which the alloy comprises by weight about:
0.66% zinc;
7.00% nickel;
0.60% copper; and
0.07% cobalt.
5. The gold alloy of any one of claim 1 in which the alloy consists essentially of the listed elements.
6. The gold alloy of any one of claim 1 in which the gold is present in about 91.67%.
7. A master alloy for making a gold alloy composition, the master alloy comprising by weight:
4.8 to 18.0% zinc;
72.0 to 90.0% nickel;
4.8 to 18.0% copper; and
0.24-6.0% cobalt.
8. The master alloy of claim 7 comprising by weight:
6.0-12.0% zinc;
72.0 to 90.0% nickel;
4.8 to 9.6% copper; and
0.24-1.2% cobalt.
9. The master alloy of claim 8 in which the cobalt comprises 0.4 to 1.2% by weight.
10. The master alloy of claim 7 in which the alloy comprises about:
7.92% zinc;
84.03% nickel;
7.21% copper; and
0.84% cobalt.
11. The master alloy of claim 7 in which the alloy consists essentially of the listed elements.
12. A method of making a gold alloy composition comprising providing the master alloy of any of claims 7-10 and mixing the master alloy with gold in a ratio of about 90.9-93.0% by weight gold with the remainder being master alloy.
13. The method of claim 12 in which the gold is present in about 91.67% by weight
14. A method of making jewelry comprising manufacturing a gold alloy according to any of claims 1-4 in the form of a rod or a bar and rolling the bar or rod to a sheet having a substantially reduced thickness.
15. The method of claim 14 in which the sheet is stamped into a two or a three-dimensional part.
16. The method of claim 14 in which the sheet is manufactured into a threaded part.
17. The method of claim 14 in which the sheet is manufactured into a spring or a spring-containing part.
18. Jewelry comprising the alloy of any of claims 1-4.
19. Jewelry made by the method of claim 14.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/662,197 US20050100471A1 (en) | 2002-09-13 | 2003-09-12 | White gold alloy |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US41067102P | 2002-09-13 | 2002-09-13 | |
US10/662,197 US20050100471A1 (en) | 2002-09-13 | 2003-09-12 | White gold alloy |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050100471A1 true US20050100471A1 (en) | 2005-05-12 |
Family
ID=34555440
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/662,197 Abandoned US20050100471A1 (en) | 2002-09-13 | 2003-09-12 | White gold alloy |
Country Status (1)
Country | Link |
---|---|
US (1) | US20050100471A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007083169A1 (en) * | 2006-01-23 | 2007-07-26 | Middlesex Silver Co. Limited | Master alloy manufacturing |
US20080206091A1 (en) * | 2007-02-26 | 2008-08-28 | Guner Kuyumculuk Kalip Makina Sanayi Ve Ticaret Limited Sirketi | Novelty in the Method for the Combination of Gold and the Other Minerals |
ITPD20130002A1 (en) * | 2013-01-11 | 2014-07-12 | Legor Group S P A | COMPOSITION OF LEGA MADRE FOR THE PRODUCTION OF WHITE GOLD AND ALLOY WHITE GOLD ALLOYS. |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030012679A1 (en) * | 2001-05-30 | 2003-01-16 | Leg.Or S.R.L. | Gold alloys and master alloys for obtaining them |
-
2003
- 2003-09-12 US US10/662,197 patent/US20050100471A1/en not_active Abandoned
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030012679A1 (en) * | 2001-05-30 | 2003-01-16 | Leg.Or S.R.L. | Gold alloys and master alloys for obtaining them |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007083169A1 (en) * | 2006-01-23 | 2007-07-26 | Middlesex Silver Co. Limited | Master alloy manufacturing |
US20080206091A1 (en) * | 2007-02-26 | 2008-08-28 | Guner Kuyumculuk Kalip Makina Sanayi Ve Ticaret Limited Sirketi | Novelty in the Method for the Combination of Gold and the Other Minerals |
ITPD20130002A1 (en) * | 2013-01-11 | 2014-07-12 | Legor Group S P A | COMPOSITION OF LEGA MADRE FOR THE PRODUCTION OF WHITE GOLD AND ALLOY WHITE GOLD ALLOYS. |
WO2014108848A1 (en) * | 2013-01-11 | 2014-07-17 | Legor Group S.P.A. | Master alloy composition for producing white gold alloys and white gold alloy thus obtained |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: W.R. COBB CO., RHODE ISLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TAYLOR, ARTHUR D.;REEL/FRAME:015197/0217 Effective date: 20040212 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |