Jewelry and Gemstone Glossary of Terms

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Hallmark

A hallmark is the official mark stamped or inscribed in metal which indicates the fineness of the metal and the manufacturer. For example, a hallmark of 925 indicates the piece is 92.5% fine silver while a mark of 14K indicates the piece is 14/24 gold (see karat). Hallmarks also indicate the maker of the piece. In Britain, a hallmark is required by law and it is illegal to incorrectly mark the metal content. In the United States hallmarks are not required by law, but are customarily used by artists and designers.

The word hallmark originated in the Middle Ages in England, when silversmiths were members of the Guildhall.

Hardness

Hardness is measured using the Mohs Scale of Hardness. A substance's hardness value indicates the materials resistance to scratching and grades minerals on a comparative scale from 1 (very soft) to 10 (very hard).. In the Mohs scale, a mineral of a given hardness rating will scratch other minerals of the same rating, as well as any minerals of a lower rating. For example, sapphires and rubies have a Mohs rating of 9 and will scratch each other, as well as any mineral with a rating lower than 9. However, they will not scratch diamonds, which are rated 10. The Mohs scale of mineral hardness was devised by the German mineralogist Frederich Mohs (1773-1839) in 1812.

Hyacinth
(Jacinth)

A variety of Zircon. Color ranges: brown, orange, reddish-brown and yellow. This stone is referenced in several of the ancient birthstone tables.

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