Minerals.net
Orange-Red Coral
AMORPHOUS

Coral

Mostly calcium carbonate

Hardness
3–4
Refractive Index
1.48–1.65
Spec. Gravity
2.6–2.7
System
Amorphous
Unlike most other gemstones which are of mineral origin, Coral is organic, formed by living organisms. It forms from branching, antler-like structures created from coral polyps in tropical and subtropical ocean waters. When the coral polyps die, the hardened skeleton remains, and this material is what is used as a gemstone. Most coral is white, but nature can create coral in several other colors, including the popular orange to red forms. This Red Coral, or Precious Coral as it is often known by, is the most used gemstone form of Coral. In fact, the color known as coral is derived from the typical pinkish-orange color of many red Coral gemstones.

About

Coral is an ancient gemstone, and has been used for thousands of years. Aside from the lovely solid colors found in Coral, it can also have color zones or swirls, with white, pink, orange, and red being the most prevalent. Coral is naturally dull; polishing is required to bring out its glassy luster. Coral gemstones can be either solid or porous, depending on the polyp formation. Despite Coral's pretty colors, it is very soft and brittle, and does not make a durable gemstone. It is prone to both scratches and chipping. Due to environmental protection laws worldwide, production of Coral for the gemstone trade is on the decline.

Uses

Coral is used as cabochons and beads. It is also sculpted into small carvings such as flowers for pins and brooches. Small branches of Coral are sometimes stranded into spiky, dangling necklaces.

Varieties

✓ common  · ✗ uncommon

  • Precious Coral— Also known as Red Coral, describes the marine coral species corallium rubrum (or several related species of marine coral). Precious coral has a natural pink to red color and is the most desirable jewelry form of Coral.
  • Red Coral— Marine coral species corallium rubrum (or several related species) with a naturally colored light pink to deep red color.
  • Black Coral— Marine coral species of the antipatharia family with a black color.

Treatments & Enhancements

Most gemstone Coral is natural, but caution should be taken as some Coral, especially with a deep red color, may be dyed.

Sources

Coral is found only in tropical to subtropical saltwater environments. Regions producing coral include the Red Sea, the Midway Islands, the Canary Islands, the Taiwan and Malaysian Coast, the coast of Australia, Italy, (Sardinia), and Hawaii.

Similar Gemstones

Red Coral may be confused with Carnelian, which is much harder. White Coral may be confused with Ivory.

Faceted

See all 9 faceted photos →

In the Rough