DIAMOND

OBSIDIAN

Obsidian has the same hardness as glass, 5 to 5'/2 on the Mohs scale. It resembles glass and is actually a kind of volcanic glass. It is opoque and brittle, breaking easily into sharp splinters. It may be k, gray, brown, yellow, red, green, or blue in one color or ked. Tumbled gems are used in inexpensive jewelry. Native ~ can silver jewelry often contains black or gold obsidian cabochons, either plain or engraved.

The ancient Mexicans used obsidian for a variety of purposes, including weapons. So adept were they that they were able to strike ;e sharp enough for use as a razor or as a knife for their human sacfrices. Another use was as a mirror whose purpose was to foretell the future. One of these mirrors may have been used by a Dr. Dee, a fortuneteller favored by Queen Elizabeth I of England.

OPAL

Are the most fragile of all gems. They are between 5'/z and 61/2 Mohs scale. Although they have no cleavage, they are very brittle. Yet they are sometimes called the Queen of Gems because of their unique beauty. The name comes from a Sanskrit word, waning "precious stone."

Common opal is translucent or a milky gray or yellow and has unless it is transparent enough to facet. What we think of precious or noble opal. It has opalescence, a play of lights or fire different colors that has been likened to the flash of fireflies against a snowy background. Not that all opals are white. The particular fire is due to inclusions that contain water, and an opal ma~ contain as much as 10 percent water. For this reason, opals are far less durable than most other gems and no historic opals have ever been found.

The idea that opals are unlucky is relatively recent. To the ancients, opals were powerful amulets, protecting the wearer against myriad misfortunes, with even the power of rendering him or her invisible. According to Pliny, the Roman senator Nonnius had opal that Marc Antony wanted.

Given the choice of losing the opal or leaving Rome, he fled Rome and took only the opal with him Opals were also supposed to be good for the eyes, and in Elizabetha England were called "opthal," from which ophthalmic, pertaining tc the eyes, comes. In the Middle Ages, an opal necklace was consicered good insurance by blondes that their hair would not darken or fade.