Organic Gems | Exotic Woods
Tropical Exotic Hardwoods used in Jewelry Source: Africa, Central America, South America, South East Asia Wood as a gemstone?! Even though wood is an extremely soft material when compared to mineral gemstones, it can be very hard if it is the tropical variety. There are literally hundreds of species, and varieties of exotic hardwoods to choses from when making jewelry, but many are duplicative in terms of color and grain texture. Obviously, it is imperative to select woods that have sufficient hardness to stand up to everyday use. Corals are major contributors to the physical structure of coral reefs that develop in tropical and subtropical waters. Due to its unique and striking color, red coral has become a popular gemstone choice for jewelers in recent years. Pure red coral, also known as 'fire coral' or 'ox blood coral' is becoming very rare due to the high demand for perfect specimens used in jewelry making, and the stress that over-collection is placing on the environmental health of coral reefs. The term "exotic hardwoods" or tropical hardwoods" refers to wood made from trees that originated in the tropics or subtropics. Most of these tree varieties are evergreen, but a few are deciduous, meaning that they loose their leaves seasonally. softwoods, which are not used in jewelry, come from coniferous (producing pine cones) trees that grow in colder climates.
The primary difference between a hardwood and softwood is the presence of pores, or "vessels." These vessels typically show considerable variation in their size, shape of their perforation plates (simple, scalariform, reticulate, foraminate), and structure of their cell walls (spiral thickenings). A favorite technique for the use of these colorful hardwoods in jewelry is to laminate (glue) several varieties together in a random pattern, then cut thin sections which show the contrasting colors and textures. Janka Hardness Test for HardwoodsTo test the "hardness" of these tropical hardwoods we could not use the conventional test for gem (mineral) hardness, the Mohs hardness scale, as they would all fall outside of the lowest range of the test. The Mohs scale is a "scratch test" which all woods would easily fail. The same is true for the Vickers and Brinell hardness tests which were designed for metals.  The "Janka" hardness test was designed specifically for wood, but is similar to the Brinell test in that it measures the amount of force necessary to embed a .444-inch steel ball to a depth of half its diameter in the wood sample. The "hardness" calculation is given in lbs. per square inch of force. Exotic Hardwood Varieties
Black Palm Black Palm is heavily mottled with black flecks on a light brown background. The two interesting varieties of Black Palm are Borassus flabellifer (aka Asian Palmyra Palm, Toddy Palm) from Myanmar (Burma), and Normanbya normanbyi from Queensland, Australia, both are evergreens. Black Palm is a flowering plant in the Arecaceae family. Trees can grow to 100 feet or more. Ebony This solid black exotic wood is one of the hardest and heaviest woods, and one of the most difficult to cut. Ebony sawdust has an irritating, peppery smell, and it can easily dull most saw blades. Ebony is an evergreen that is native to West Africa (Gabon), Southern India and Sri Lanka (Ceylon Ebony). Ebony has been revered for thousands of years, and the word "ebony" derives from the Ancient Egyptian word hbny. Cocobolo There are two varieties of Cocobolo: Diospyros crassiflora or Dalbergia retusa, both evergreens from Costa Rica, Central America. Cocobolo is a very dramatic wood, with deep orange and reddish-brown zones contrasted by lines of very dark brown or light yellowish-tan (sapwood). Cocobolo is very dense, and can be polished to a glassy finish. Rosewood There are several varieties of rosewood which include Brazilian Rosewood (Dalbergia nigra) and Indonesian Rosewood (Dalbergia latifolia) Brazilian Rosewood is a species of legume in the Fabaceae family, which is only found in the forests of Bahia in Brazil. Due to its endangered status, it is CITES-listed, and illegal to trade. Osage Orange Osage Orange (aka Bodark, Horse-apple) is a yellowish hardwood which is a deciduous plant species, with the male and female flowers on different evergreen plants. Trees grow to a maximum height of around 50 feet. The uncured wood is filled with a sticky white latex sap, and the sawdust has a faint odor of citrus. Pernambuco Pernambuco (aka Brazilwood, Pau-Brasil, Pau-de-Pernambuco) is an evergreen that produces a heavily banded wood with light or dark brown stripes, and an orange-red heartwood. Pernambuco is a dense wood that is used for making bows for string instruments, and the tree also is used to make a red dye called "brazilin." As the name implies, this wood comes from the Brazilian state of Pernambuco. Purple Heart Purple Heart (aka Amaranth, Violetwood, Tananeo, Saka) is a deep violet-purple exotic wood that is found in Central and South America. Purple Heart includes over twenty species of Peltogyne. Purple Heart is lighter when first cut, and can darken with age. Verawood Verawood (aka Maracaibo Lignum Vitae, Vera Wood) is an evergreen that produces a very hard wood that is heavily banded with light and dark brown stripes. The verawood tree native to Colombia and Venezuela. Tulipwood Brazilian Tulipwood (aka Poplar) is an evergreen that produces a dense, heavily-banded wood of light tan and deep reddish-brown. In the nineteenth century Brazilian tulipwood was thought to be the product of Physocalymma scaberrima, but in the twentieth century it became clear it was yielded by a species of Dalbergia. Zebrawood As the name implies, Zebrawood (aka: Bois De Zebre, Brazilian Koa, Chibatao, Guarita, Tigerwood, Urunday-Para) is an evergreen that produces a heavily-banded wood of light yellow-brown with very pronounced dark stripes. Ziricote Ziricote (aka Siricote, Zircote) is an evergreen that produces a dense, dark brown (almost black) wood with wavy swirls of greenish-brown. Ziricote is found in Belize, Guatemala, and Mexico.  Bibliography and Reference on Ivory 1. Paul R. Shaffer, Rocks, Gems and Minerals 2. TED, Elephant Ivory Trade Ban 3. M. Springate, Identifying Different Types of Ivory 4. R. Weiss, The Art of Scrimshaw 5. NMGCS, National Milk Glass Collectors Association 6. CBS 60 Minutes, Poachers Leaving Elephant Orphans |
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