US1727425A - Method of grinding or polishing diamonds - Google Patents

Description

Patented Sept. 10, "1929.

UNITED STATES PATENT oFrICL CLAES W. BOHAN, OI BROOKLYN, NEW YORK, ASSIGNOR TO JOYCE-ROBBED DIA- MOND TOOL DEPARTMENT, INQ, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

METHOD O1 GRINDING OB POLISHING DIAMONDS.

Io Drawing.

This invention relates to the art of grinding or polishing diamonds. a

In that art as now practiced it is customary to use a lapidarys wheel composed of suitable 5 material-that is impregnated with diamond dust. Such wheel is expensive, and by means of it plane surfaces only can be ground; for instance, the girdle or equator surrounding the diamond and separating the upper and lower parts thereof cannot be polished, and the diamond can be given only the stereotyped shape composed of facets since no curved sur face can be polished. This is due to the fact that when using the previously known lapidarys wheel the diamond can be polished only in a certain direction with respect to the.

grain. Thus, in grinding the facets, it is necessary not only to so turn the diamond as to present the different facets successively, but care must also be taken to so present the facet with respect to the direction of rotation of the wheel or lap that the grinding or pol ishing of the diamondtakes place in a certain direction with respect to the grain. Some diamonds of undoubted purity and excellence have no definite stratification or grain and can therefore not be properly polished and used for gem purposes, and these, otherwise valuable diamonds, are rendered relatively valueless and can be used only for mechanical pur' poses or they must be divided into small stones efore they can be used, if at all, for gem purposes. So also the so-called carbon diamonds, which are used only in the mechanical arts and for commercial purposes and which are harder and more amorphous than diamonds used for gem purposes, cannot be given the keen edge that is so desirable for the uses to which these diamonds are put. These conditions are well-known and are due entirely to the inability to grind or polish diamonds otherwise than in a certain direction with respect to the grain".

The condition in the art today may therefore be summarized as follows:

1. The shape that can be given-diamonds to be used for gem purposesis limited-to the production of plane surfaces or facets; no curved surfaces can be polished and the girdle of the diamond cannot be polished.

I Application flled August 5, 1921. Serial No. 490,166.

. 2. There is a great loss because of imperfect stratification or grain in diamonds that would otherwise be valuable.

3. Diamonds of an amorphous character used for mechanical purposes cannot be given 65 as keen a cutting edge as is desirable.

4. The lapidarys wheel or lap heretofore used is expensive.

5. The process of grinding or polishing diamonds is slow because each facet must be so adjusted with respect to the rotation of the wheel or lap that grinding or polishing takes place in a certain direction with respect to the grain. Highly skilled labor is necessary for this work.

These manifest disadvantages I have overcome by the discovery of a substance that can be used for a lapidarys wheel and which exhibits the unexpected property of grinding or polishing diamonds regardless of the grain, 7 or without respect to the Stratification or grain of the diamond.

This substance is known as Arkansas stone, and is a stone of such texture that diamonds will be cut, ground or polished without regard to their grain or stratification. It is much cheaper than the material of which the regulation lapidarys wheelis made and, by means of it, curved surfaces can be produced in gem diamonds; the culet of gem diamonds can be polished; diamonds having imperfect stratification can be used for gem purposes without first subdividing them into smaller stones; diamonds used in the mechanical arts can be given a keener edge; and the speed of cutting, grinding or polishing diamonds is materially increased because of the absence of the necessitv of properly adjusting each facet with respect to the direction of rotation of the lap.

So also the skilled labor heretoforeused is no longer necessary to carry out the process. I also find that,.if desired, the peripher of the lap, as well as its flat top surface, may be used for the purpose of cutting, grinding or polishing diamonds.

It will be understood from the foregoing that by my invention the necessity for im- 'pregnating the lapidarys wheel with diamond dust is obviated.

I claim:

The method of grinding or polishing a, diw mond which conslsts in abrading the same, regardless of its grain, against a surface comp d of Arkansas stone.

igned at New York, in the county of New York and State of'New Ybrk, this 2nd day of August, 1921.

CLAES W. BOMAN.