11.10 CT CERTIFIED SPHALERITE ROUND GEMSTONE

Sphalerite - History and Introduction

Sphalerite is a zinc ore mineral that typically contains iron. When it has a high iron content, Sphalerite is an opaque black. On the other hand, gem-quality material has a low iron content, resulting in transparent crystals. Due to its lack of hardness, it is mainly a collector's gemstone. One of the most notable characteristics of Sphalerite is its high dispersion (0.156). The dispersion of Sphalerite is over three times that of diamond, which has a dispersion of 0.044. In addition, Sphalerite has remarkable "fire, " separating visible light into colors by refraction or diffraction. In simple terms, this refers to the flashes of color seen when Sphalerite is turned in the light.

Due to its composition, Sphalerite is also known as "zinc blende." The name "sphalerite" comes from the Greek word "sphaleros," which means "deceptive." Sphalerite is easily mistaken for galena, the mineral form of lead sulphide. Gem-quality transparent Sphalerite is rare. Sphalerite is typically yellow, orange, or red. A black, iron-rich variety of Sphalerite is called marmatite.

Identifying Sphalerite

Sphalerite is identified by its yellowish, orange, or honey-brown color and characteristic resinous to adamantine luster. Its high dispersion, cleavage in six directions, and high density also help to distinguish Sphalerite from other gemstones of a similar color. Also, a streak test (crushing the mineral into a powder or swiping the mineral across a "streak plate") produces a sulphurous odor, making Sphalerite unmistakable.

Sphalerite; Origin and Gemstone Sources

Sphalerite deposits are found in Bulgaria, Canada, the Democratic Republic of the Congo, Mexico, Namibia, Spain, the USA, and Zaire.

Buying Sphalerite and Determining Sphalerite Gemstone Value

Sphalerite Color

Sphalerite can be colorless, yellow, orange, red, or green. Most gemstones tend to range from pale yellow to deep fiery orange. The lighter-colored gemstones display the most extraordinary dispersion. Red shades of Sphalerite are also known as "ruby blende." Colorless sphalerite specimens are rare.

Sphalerite Clarity and Luster

Sphalerite gemstones are rarely inclusion-free, except in small sizes. The greasy to the adamantine luster of Sphalerite is remarkable. When buying sphalerite gemstones, select specimens with the best clarity, which generally exhibit the most extraordinary dispersion or "fire."

Sphalerite Cut and Shape

Sphalerite is usually faceted to maximize its brilliance. It is available in various shapes, such as octagons, trillions, squares, and rounds, and fancy shapes, such as ovals, pears, and cushions. However, Sphalerite is challenging for gem cutters because of its brittle tenacity, softness, and perfect cleavage in six directions.

Sphalerite Treatment

Synthetic Sphalerite is known to exist. However, natural Sphalerite is also available.