Hardness (continued)

Minerals Used in Testing Hardness. For testing stones that are more enthusiastically than a document the understudy

ought to give himself the accompanying arrangement of materials:

1. A little gem of carborundum. (Most tool shops have example precious stones as alluring

commercials of carborundum as a grating material, or the Carborundum Co., Niagara Falls,

N. Y., will supply one.)

2. A little gem of sapphire (not of pearl quality, but rather it ought to be straightforward and minimized. A

pale or dry Montana sapphire can be had for a couple of pennies of any mineral vendor).

3. A little obvious topaz gem. (The unadulterated white topaz of Thomas Mountain, Utah, is[56] amazing;

or then again white topaz from Brazil or Japan or Mexico or Colorado will do. Any mineral house can

outfit little gems for a couple of pennies when not of extraordinarily fine crystallization.)

4. A little quartz gem. (This might be either amethyst or quartz-topaz or the basic dull

assortment. The fine, sharp, boring precious stones from Herkimer County, N. Y., are brilliant. These are

exceptionally economical.)

5. A section of a precious stone of feldspar. (Regular orthoclase feldspar, which is as often as possible of a

caramel pink or tissue tone, will do.)

These five test stones address the accompanying levels of hardness:

1. Carborundum is more enthusiastically than any jewel material yet precious stone. It will scratch sapphire and ruby,

which are appraised 9 in hardness, henceforth we may call carborundum 91⁄2 in the event that we wish. It is, in any case,

particularly milder than precious stone, and the last will scratch it upon the smallest pressure.[57]

2. Sapphire, of hardness 9, scratching any jewel material with the exception of precious stone.

3. Genuine topaz, of hardness 8. It is scratched by sapphire (and, obviously, ruby), likewise by

chrysoberyl (which is consequently appraised 81⁄2), however scratches most different stones. Spinel (which is too

appraised as 8 in hardness) is actually somewhat harder than topaz.

4. Quartz, of hardness 7, and scratched by every one of the past stones yet scratching those that were

recorded above as of less hardness than a document.

5. Feldspar, of hardness 6, subsequently marginally gentler than a document and respecting it, yet scratching the

stones moreover appraised as 6 when applied persuasively to them. Additionally scratching stones evaluated as less

than 6 on slight pressing factor.

We should next consider how these minerals might be securely utilized upon pearl material. Clearly it

would be far more secure to utilize them upon unpleasant diamond material than upon cut stones. Notwithstanding, with

care and some little expertise, one[58] may make hardness tests without specific peril to fine cut


The best approach is to apply the cut stone (ideally its support, or if that is so set as not to be

accessible, a corner where a few features meet) tenderly to the level surface of one of the milder test

stones, drawing it daintily along the surface and noticing the vibe and hoping to check whether a scratch

results. In the event that the test stone is scratched invest the following more effort test stone comparably. Try not to endeavor to utilize

the test stone upon any important cut stone. Continue as above until the diamond meets a test stone that

it doesn't assault. Its hardness is then likely equivalent to the last mentioned and maybe whenever squeezed persuasively

against it a slight scratch would result, however it isn't fitting to turn to substantial pressing factor. A light

contact ought to be developed in this work. Having now a sign regarding the hardness of the

obscure jewel turn upward in the table of the past exercise those pearls of comparative hardness and afterward

by the[59] utilization of a portion of the tests previously given choose which of the stones of that level of

hardness you have. Never depend upon a solitary test in distinguishing a jewel.