Good afternoon lucia4 an thank you for the question. I hope you find
the following information useful.
Coral used in jewelry making ranges in color from pale pink (called
angelskin coral) to orange to red to white to black. The most valued
colors are deep red (called noble coral) and pink.
Red Coral: The most valued coral of all, favored worldwide for its
hardness, beauty, and sanguine hue. Red Coral is brought up from the
sandy bottom of the Mediterranean, and the Gulf of Naples near Genoa.
It is also found off Algiers and Tunis on the African side, in the
waters of Sardinia, Corsica, Catalonia and Provence, as well as along
parts of the French and the Spanish seaboard.
Precious, or Noble Coral: A type of red coral called Corallium Rubrum,
or Corallium Nobile, Precious coral can be found in the Mediterranean,
Sardinia and Sicily, as well as in Tunis, Algeria and Morocco.
Black Coral: This coral is a horny substance particularly good for
carving and molding ? it actually bends when it is warmed! The black
hue is believed to be coral in the first stage of decay, since the
color only persists a little below the surface. Once abundant in the
Persian Gulf, a similar type is found in the Mediterranean.
Blue Coral: As with Black Coral, this variety is thought to be coral
in the first stage of decomposition, since the color usually extends
only just below the surface. It is known both as Allopora Subviolacea
and Akori. This unusual variety has been found off of Cameroon.
Golden coral: Divers off Maui, in Hawaii, have brought up this pretty
variety of coral, which has a resinous or lacquered texture.
It used to be thought that coral protected the wearer, so it was a
traditional gift to children.
Since it is composed of calcium carbonate, coral will effervesce
(fizz, bubble or spark) if touched with acid. I believe you can
effectively ?test? your coral jewelry using this method but if you
insist on doing it yourself, be very careful as we all know that acid
can be very harmful if it comes in contact with skin or other things.
Coral is also porous so there will be some "imperfections" in the
coral beads. Coral is also softer than glass and other gem materials
with a hardness of only 3.5. As a result it should be stored carefully
to avoid scratches.
Although your jewelry could be genuine, to be sure you really need to
get a professional evaluation by a certified jewelry appraiser. I can
give you a list of appraisers in your area if you tell me the city &
state you live in. Otherwise, you may want to use the Superpages
database found at:
( http://www.superpages.com/yellowpages/C-Jewelry+Appraisers/S-/T-/ )
If this answer requires further explanation, please request
clarification before rating it, and I'll be happy to look into this
Google Answers Researcher
Jewelry & Gem Dictionary
( http://www.original-diamonds.com/dictionary_c.php )
( http://jewelry.about.com/od/coral/ )
Clarification of Answer by
04 Aug 2005 16:17 PDT
If I remember by chemistry correctly, calcium carbonate reacts with
acids to produce carbon dioxide gas, which we observe as bubbles. It
can be tested using regular household vinegar.
According to most chemistry sites on the net, the "acid test" the
geologists use to test minerals uses either dilute hydrochloric acid
(<10% solution) or dilute acetic acid (vinegar).
Additionally, Nancy Stacy, a certified jewelry appraiser based in
Walnut Creek, CA, has verified that the methods mentioned above would
be used by a gemologist to test if the coral was genuine or not.
Additionally, they could take a Refractive Index reading, and with
microscopic could observe growth lines, small pits and areas of
branching. If you have any other questions for her, you can email her