Gemstone

Lore & Background

Gemstones have been classified since ancient Greek times into precious and semi-precious categories, with precious stones traditionally being emerald, ruby, sapphire, and diamond. This distinction reflects rarity and quality, though modern values do not always align—for example, a green garnet called tsavorite can be more valuable than a mid-quality emerald. Other stones like amethyst were once considered precious until large deposits were found in Brazil in the 19th century. Gemologists identify gemstones by chemical composition, crystal system, and habit. For instance, diamonds are carbon with a cubic crystal system often found as octahedrons. Gemstones are further classified into groups, species, and varieties—ruby is the red variety of corundum, while other colors are sapphire. Characteristics include color, optical phenomena, luster, refractive index, hardness, cleavage, and fracture. Grading systems vary: diamonds are graded using the GIA system with 10x magnification, while other gemstones are graded by naked eye. The 'four Cs' (color, cut, clarity, carats) apply to all gemstones, but cut is primary for diamonds, while color purity is primary for colored stones. Numerous laboratories worldwide provide grading reports, including GIA, IGI, HRD Antwerp, and others.

Reader's Guide

Gemstones hold significance as both ornamental objects and subjects of scientific study. Their value is governed by factors such as clarity, rarity, freedom from defects, beauty, and market demand. The traditional precious/semi-precious distinction persists in reputation but is not strictly followed in modern trade, where diamonds, rubies, sapphires, and emeralds still command high regard. Rare gemstones like painite and red beryl are known mainly to connoisseurs. Gemstones also have proponents in energy medicine who value them for alleged healing powers, though this is separate from their aesthetic and commercial roles. The existence of multiple grading laboratories reflects the complexity and global nature of the gemstone trade.

Did You Know?

• A gem expert is called a gemologist; a gem maker is a lapidarist or gemcutter; a diamond cutter is a diamantaire.
• The traditional precious stones are emerald, ruby, sapphire, and diamond; all others are considered semi-precious.
• Ruby is the red variety of corundum, while any other color of corundum is considered sapphire.
• Amethyst was considered a precious stone in ancient Greece until bulk discoveries in Brazil in the 19th century.