Therefore each liquid will isolate the stones in its own group by compelling them to float on its surface; commencing with the heaviest and giving to the groups the same letters as the liquids, it is seen that—
Group A.—Isolates gems with a specific gravity of 4.7963 and over 4.70; in this group is placed zircon, with a specific gravity of from 4.70 to 4.88.
Group B.—Stones whose specific gravity lies between 3.70 and under 4.7963.
| Garnets, | many varieties. See Group D below. | ||
| Almandine | 4.11 | and occasionally to | 4.25 |
| Ruby | 4.073 | " | 4.080 |
| Sapphire | 4.049 | " | 4.060 |
| Corundum | 3.90 | " | 4.16 |
| Cape Ruby | 3.861 | ||
| Demantoid | 3.815 | ||
| Staurolite | 3.735 | ||
| Malachite | 3.710 | and occasionally to | 3.996 |
Group C.—Stones whose specific gravity lies between 3.50 and under 3.70.
| Pyrope (average) | 3.682 | ||
| Chrysoberyl | 3.689 | and occasionally | to 3.752 |
| Spinel | 3.614 | " | 3.654 |
| Kyanite | 3.609 | " | 3.688 |
| Hessonite | 3.603 | " | 3.651 |
| Diamond | 3.502 | " | 3.564 |
| Topaz | 3.500 | " | 3.520 |
Group D.—Stones whose specific gravity lies between 3 and under 3.50.
| Rhodonite | 3.413 | and occasionally to | 3.617 |
| Garnets | 3.400 | " | 4.500 |
| Epidote | 3.360 | " | 3.480 |
| Sphene | 3.348 | and occasionally to | 3.420 |
| Idocrase | 3.346 | " | 3.410 |
| Olivine | 3.334 | " | 3.368 |
| Chrysolite | 3.316 | " | 3.528 |
| Jade | 3.300 | " | 3.381 |
| Jadeite | 3.299 | ||
| Axinite | 3.295 | ||
| Dioptase | 3.289 | ||
| Diopside | 2.279 | ||
| Tourmaline (yellow) | 3.210 | ||
| Andalusite | 3.204 | ||
| Apatite | 3.190 | ||
| Tourmaline (Blue and Violet) | 3.160 | ||
| Tourmaline (Green) | 3.148 | ||
| " (Red) | 3.100 | ||
| Spodumene | 3.130 | and occasionally to | 3.200 |
| Euclase | 3.090 | ||
| Fluorspar | 3.031 | and occasionally to | 3.200 |
| Tourmaline (Colourless) | 3.029 | ||
| Tourmaline (Blush Rose) | 3.024 | ||
| Tourmaline (Black) | 3.024 | and occasionally to | 3.300 |
| Nephrite | 3.019 |
Group E.—Stones whose specific gravity lies between 2.50 and under 3.000.