Glossary of Terms & Facts

Turquoise

Names and Properties of Turquoise The word 'turquoise' dates back to the 17th century and is derived from the Old French 'turquois' meaning Turkish. The gemstone was first brought to...

Characteristics and Physical Properties Tungsten is a hard steel-grey metal that is often brittle and hard to work. Purified, monocrystalline tungsten retains its hardness and becomes malleable. Tungsten has the...

Tumbaga

Composition and properties Tumbaga is an alloy of gold and copper. It has a lower melting point than gold or copper alone. Tumbaga is harder than copper but remains malleable....

Tsavorite

Characteristics of Tsavorite Tsavorite is a variety of the garnet group species grossular. It has a specific gravity of 3.60-3.68. Tsavorite has a refractive index of 1.740. The dispersion of...

Troy weight

Etymology and History of Troy Weight Troy weight takes its name from the French market town of Troyes. The name 'troy' is first attested in 1390. Charles Moore Watson proposes...

Trilliant cut

Introduction and History of Trilliant Cut The trilliant cut was introduced by the Asscher brothers in Amsterdam. Leon Finker created his version of the triangular brilliant cut diamond, called the...

Transparency and translucency

Transparency and Translucency Transparency: Shining through, from Latin 'transparere' meaning be visible Translucent: Shining through, from Latin 'translucere' meaning to shine Opaque: Darkened, from Latin 'opacus' Late Middle English: Influenced...

Tourmaline

General Information about Tourmaline Tourmaline is a mineral that belongs to the tourmaline group. It is a complex borosilicate mineral with a wide range of colors. Tourmaline is classified into...

Toughness

Definition and Measurement of Toughness Toughness is related to the area under the stress-strain curve. A material must be both strong and ductile to be tough. Brittle materials lack ductility...

Tortoiseshell

Uses and Applications of Tortoiseshell Tortoiseshell was widely used in ancient times in the North and in Asia. It was used in the manufacture of combs, small boxes, frames, and...

Topaz

Etymology and History The name topaz is believed to be derived from the Greek word 'Τοπάζιος' or 'Τοπάζιον'. It is named after St. Johns Island in the Red Sea, where...

Tool

Definition and History of Tools Tool use is the external employment of an object to modify another object or organism. Benjamin Beck proposed a widely used definition of tool use...