Published: August 2011
by George Williams, JTV Senior Gemstone Buyer
From the colorful Caribbean island of Honduras comes an intriguing black gemstone, the black opal. While you may not think of Honduras as a source for opal, the country has some of the oldest recorded opal mines in the world.
Honduras is situated between North and South America, in the very heart of Central America. Bordered by Guatemala, El Salvador, and Nicaragua, it has two coastlines. Surrounded by the tropical Caribbean and the enormous Pacific, Honduras is steeped in rich cultural traditions. Famous for its archaeology, it has one of the Mayan world’s most beautiful and best preserved sites, Copán.
This unspoiled setting for natural beauty is also home to one of the most beautiful of gems, Honduran black opal. The Honduran black opal is a unique variety of black matrix opal. Stones are beautifully speckled and appear almost galactic in nature. They are of volcanic origin forming in basalt belts which gives them their natural black body color. As with every opal, the colors and patterns of each stone are never exactly alike and Honduran black opal is no exception. Black opal is a unique (and highly collectible) gem to add to a collection. Black opal also makes outstanding jewelry because the gem can easily stand alone or be combined with any color.
A meandering hillside peppered by large blocks of volcanic black basalt is the source for JTV’s Honduran black opal. Workers hand chisel the boulders to extract small veins of thin, colorful precious opal. The material is found as horizontal bands within the vesicular black basalt and great care is exercised during the extraction process. The opal, having no cracks or holes to fill, merely solidified within the rock itself. As a result, the entire opal-filled rock is fashioned into gems. There are many grades of this material ranging from that of little value (and often sold in bulk sacks) to the premium, intensely fiery material usually sold by the gram.
The mining area itself isn’t easily accessible—the trail to the mountainous location is only 3 feet wide. Once the rough is mined, it must be brought down the hillside by donkeys.
Once the rough reaches the cutter, it is fashioned into striking cabochon gems since smooth, rounded surfaces show the colors best. Since black matrix opal isn’t like ‘regular’ opal, its blended formation can frustrate opal cutters who are only familiar with the glassy types of opal. The reason for this is that regular opal is sensitive to rapid temperature fluctuations requiring that a lapidary keep the stone from suddenly overheating while working it. Black matrix opal is just the opposite. The only way to achieve a good polish is to create drag by slowing down the rpm’s while still supplying considerable heat.
Due to the porous structure of the matrix, finished gemstones are often given a quick, hot resin bath and then scrubbed and cleaned. The resin acts as a barrier and helps to prevent the gems from absorbing other substances. This procedure is similar to the one used with emeralds. The resin does not coat the stone or harden it. Honduras black matrix opals are naturally black and they are NOT dyed by way of sugar/acid treatments. Honduran black opal is much less expensive than sugar treated matrix opal at about 1/10 of its price. As with leopard opal from Mexico, Honduran black opals needs LOTS of light to best observe their fine play of color! Prepare to be mesmerized when you take your gem out into the sun where the play of color quickly comes to life.
Honduran black opal doesn’t have the problems of heat sensitivity and brittleness that other opals have. While crazing is well known in other varieties, these gems never crack!
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