Jewelry and Gemstone Glossary of Terms

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Sardonyx

Sardonyx is a banded variety of chalcedony characterized by parallel bands of brownish red sard and white translucent onyx. Often cut en cabochon, it is also used for intaglios and cameos. While sardonyx is found naturally in bands of brown, brownish-red and white, much of that found on the market today is actually dyed agate.

Schiller

Also called labradorescence, it is a colorful play of light across the cleavage planes that is displayed in some minerals. The term labradorescence is derived from the mineral Labradorite which displays this attribute.

Spectrolite, the form of labradorite found only in Finland, has the most vibrant colors ranging from light blue, aqua, green, gold and red to dark blues. Some exceptional stones will exhibit all of these colors.

Semiprecious Gemstone

Any stone that is not classified as precious . Some examples are: turquoise, aquamarine, agate, jade, pearl, rose quartz, aventurine.

There is a great debate among jewelers and gemologists who believe the terms "semi-precious" and "precious" are not appropriate because a flawed emerald, diamond or sapphire is actually NOT more precious than a beautiful unflawed tourmaline, amber or lapis lazuli.

The reasoning behind this debate is that the individual stone itself is the designator and calling a stone "semi" precious is a misnomer. Therefore, in recent years gemologists and jewelers have applied the term "gem" or "gemstone" to stones used in jewelry and only those who haven't yet been educated about the difference in terms still use semi precious to refer to a stone.

The luster of a gemstone having a smooth, gleaming surface similar to silk or long silky fur. Tiger's eye exhibits a silky luster.

Slab

A slab is a broad, flat, relatively thin piece of stone cut from a larger chunk of stone. Lapidaries use slabs when cutting cabochons or material for jewelry inlay work.

Spectrolite

Spectrolite is a labradorite feldspar. Spectrolite is the trade name given to labradorite from Finland which is the most beautiful and vibrantly colored of all labradorites. It was found in 1940 when the Finns were building a defense line during World War II.

The play of color in the stone is called "schiller" or "labradorescence" and includes all the shades of the spectrum including rich peacock blue, bright aqua, golden yellow, reddish orange, greens and red.

Sterling Silver

Sterling is silver with a fineness of 925 parts per thousand or 92.5% silver and 75 parts per thousand or 7.5% copper. Copper is added to the alloy to increase the silver's hardness.

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