What is a gem?

A gem is generally defined as any mineral that is highly prized for its beauty, durability, and rarity, is used for personal adornment, and has been enhanced in some manner by altering its shape—usually by cutting and polishing. A wider definition includes a few rocks, such as obsidian, and a few organic substances, such as amber (a fossilized resin). By far the majority of gems, however, are cut from the crystals of minerals. Precious metals are not considered to be gems, nor are items carved from minerals but not used for personal adornment, such as figurines, bowls, or vases.

Beauty

Diamonds Beauty

Blue sapphire, prized for its beauty

The first quality a gem must possess is that of beauty. This is subjective: some may prize a gem’s interplay of light and color, while others may first be drawn to a gem’s intricate cut. With an almost endless combination of color, shape, and fire (play of light), gemstones are capable of a range of aesthetic styles.

Durability

Diamond, the hardest gemstone Goharbin Blog

Diamond, the hardest gemstone

Hardness or toughness in a gem is a desirable quality, suggesting enduring value. Some gems require care to prolong their longevity. Certain gems resist chipping or scratching, but fade after long exposure to direct light; dry environments may cause some to crack, while others are susceptible to damage from acids.

Rarity

Taaffeite, noted for its rarity

Taaffeite, noted for its rarity

A gem may be rare for a number of reasons. The gem material itself may be rare, such as emerald, or a more common material may exhibit an unusual color or clarity. Some particularly soft or fragile stones are rare in cut form, since they require the work of highly skilled lapidaries.

Other Considerations

Tanzanite, both rare and difficult to cut

Tanzanite, both rare and difficult to cut

The desirability of a gem can depend on factors besides beauty, rarity, and durability. Gems may be symbolic of power, such as those mounted in crowns, or valued for their history or circumstances of origin. They may also be prized for their connection to astrology or mysticism, for their geological associations, or as fashion items.