Identification Of Moonga / Coral
The chemical composition of organic gemstone – coral is calcium carbonate (CaCO3), a small amount of magnesium carbonate (MgCO3), a trace amount of iron oxide, and 1.5% to 4% organic matter. Its hardness is 3.5 on the Mohs scale. The specific gravity (S.G.) ranges between 2.60 and 2.70 for carbonate types and 1.30 and 2.20 for horny types. The refractive index (R.I.) lies between 1.486 and 1.658.
Synthetic, Duplicates, and Copy
Synthetic red coral, Gilson created coral, glass, plastic, reconstructed shells, stained marble, conch pearls, wood, horn, etc.
Origin place or source country
The Mediterranean and the red sea are its primary producers. Other producers include Australia, India, Italy, and Japan. It is found mainly in regions with tropical and subtropical environments. Italian coral is the most popular and in high demand, as it is the finest one.
Identification / How to check
1. Milk Test
Take a glass of milk and put your Ratna in it. Now carefully observe the colour of the milk after a few minutes; if the colour changes to a slight red or pink, it is real. If the colour of the milk does not change, it will be a fake or an imitation.
2. Vinegar Test
Take a bowl of diluted vinegar and place the coral in it. If it starts making bubbles, it’s real because coral is made up of calcium carbonate; when calcium carbonate comes in contact with an acid, it produces bubbles.
This test, however, is not considered very good because coated fake coral can exhibit the same effects. One can also perform this test with nitric acid (lemon juice) and look for bubbles or effervescence.
3. Scratch test
Try to scratch this stone with your nail and carefully listen to the sound it produces. If it sounds like the scratching sound of glass or plastic, it’s probably a fake one made up of plastic or glass.
4. Turmeric Test
Take a piece of raw turmeric and rub it against the stone; if it leaves a red mark on the turmeric, it is a fake or an imitation of a coral, not a real one. Turmeric colour will not change if it’s a natural coral.
5. Magnification
Wavy, parallel, fibrous structure; tiny cavities (polyp holes)
6. Chemical test
React with vigorous effervescence to dilute acid, such as hydrochloric acid.