Hydrophane online shopping search

With the emergence of opal production in Wollo, Ethiopia, the supply of hydrophane opal has increased significantly. This deposit offers beautiful material at a fraction of the price of similar-looking opal from several other sources, including Australia and Brazil. However, most of the opal from Wollo is hydrophane, which simply means it is porous enough to readily absorb water, much like a sponge. This property can occasionally cause durability issues that may lead to significant cracking, depending on the porosity of the material and how included it is. In general, it is difficult to predict if this material will crack when immersed, but the potential is certainly higher in hydrophane opal than in nonporous material. In hydrophane opal with a bodycolor other than white, there is the distinct possibility of artificial coloration, since stones that absorb water also absorb dye (N. Renfro and S.F. McClure, “Dyed purple hydrophane opal,” Winter 2011 G&G , pp. 260–270). While this ability to absorb water is not proof of dye, it calls for extra caution when examining an opal for color modification, especially if it has a bodycolor that can exist naturally, such as orange.

With white or colorless opals, checking for dye is…

Recently in GIA’s Bangkok lab, an approximately 4 cm piece of rough hydrophane opal was fabricated into five slices for various treatment experiments. Each slice was approximately 0.5 cm thick. Only clean tap water was used in the cutting process, and no other materials besides opal were involved. The opal slices showed a whitish, cloudy appearance in daylight and appeared light brown to brown in calibrated diffused light.

After the cutting step, all five slices underwent specific gravity testing, which gave SG values of approximately 1.93 ±0.03. While immersed in water, the slices displayed obvious weight gain and improved transparency, which indicated that the material was hydrophane opal (figure 1).

The water-absorbing ability of the opal was found to vary through the whole piece, resulting from its non-uniform porosity, and could be calculated as percentage weight changes in water, ranging from 5% to 13%. It took approximately one week to restore the opal’s original weight and appearance.

Two slices were then selected for oil and Opticon treatment experiments. The treatment procedures were identical. The pieces of opal were heated to approximately 80^°C and then placed in warm oil or Opticon of the same temperature under vacuum conditions. They…