Meet Coral: A Gemstone That is Not Really a Stone

When the coral polyps die, the hardened skeleton remains, and this material is what is used as a gemstone.

Did you know that 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.

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.

Precious coral belongs to a small, but important group of gemstones, which technically are not stones at all. Rather than being minerals with crystalline structures like most colored stones, coral is formed through a biological process and thus belongs to an elite class of organic gems. Although the class of organic gemstones is rather small, there are a number of very unusual and important gemstone varieties within the group.

There are a few materials that can be mistaken for coral owing to similarities in color or texture, including conch pearl, carnelian (red agate), rhodonite, spessartite garnet, glass, horn, rubber (gutta-percha), bone and plastic. That is why you might find it useful to learn some more about this unusual gemstone.

Read on to find out the most important facts about coral.

Highly-priced for intense color

Coral is among the most ancient of gem materials, used for adornment since prehistoric times. Coral is an organic gem, calcium carbonate with a trace of carotene, deposited by tiny sea creatures living in the depths of warm seas in huge colonies. It grows in branches that look like underwater trees.

The hard skeleton of red coral branches, which is naturally matte, is polished to a glassy shine. It exhibits a range of warm reddish pink colors from pale pink to deep red and sometimes also orange-ish red.

Most coral used in jewelry is found in the Mediterranean Sea or in the Pacific off Japan and Taiwan. Coral is also found in Algeria, Tunisia, Spain, Italy, France, Corsica, Sardinia, Sicily and India. Italian Coral is particularly famous. The finest specimens come from Sardinia and Tunisia; larger, less fine ones from Japan and China.

Due to its intense and permanent coloration and attractive luster, precious coral has been harvested since antiquity for decorative and ornamental jewelry use.

Precious coral is often used for beads in string jewelry such as necklaces and bracelets. You will sometimes see branch-like pieces drilled and strung as spiky necklaces.

Cabochons and carvings of flowers or other ornamental objects are quite often used for the making of pendants, pins, and brooches.

Coral is not recommended for everyday rings, but if set in protective-style settings they can be worn in occasional-wear rings with care.

Coral is highly-prized as a substance believed to be endowed with mysterious sacred properties. It is a symbol of modesty, wisdom, happiness and immortality. It is commonly known to remedy spasms of intestines, sleeplessness, and bladder stones.

Coral can reduce stress and fears and combats foolishness, nervousness, fear, depression, panic and nightmares. Coral is used to attract success and wealth and strengthens foresight, and some say it is a good aid for meditation or visualization.

It’s important to identify

Coral is an organic material, and like other organic gemstones, it is not an especially hard or durable gemstone. It has a hardness rating of 3 to 4 on the Moh’s scale, which can easily help distinguish and identify coral from similar colored gemstones such as carnelian, rhodonite or spessartite garnet.

White and red coral with a calcium carbonate composition has a specific gravity or density of 2.60-2.70 and a refractive index of 1.486-1.658. These specific gemological properties, combined with coral's translucent to opaque form, can easily help identify natural coral from imitations or similar gemmy materials.

Only the corals that grow slowly and live long are selected for jewelry and other ornamental purposes. The intensive collection of reefs threatens them. If you wish to buy the coral jewelry from overseas, it is important to make sure that you find out if you should take a CITES permit. When you are buying it at home, always enquire from the retailer whether the coral is imported with the required CITES permit.

In fact, specialists say there is a well-proven test for identification of real coral. If real coral is placed in a glass of cow's milk, the color of the milk will appear pink or take on a red tinge. Imitation coral will not affect the whiteness of milk.

Coral is beautifully complemented by sterling silver beads and components. Pair with turquoise or amber for statement pieces and enjoy the style power of wearing red.