Hemimorphite has an unusual characteristic: a change in temperature or pressure induces an electrical charge in the stone. The bad news is that static attracts dust and dirt, so unfortunately any jewelry will need cleaning on a regular basis.
Also known as calamine, hemimorphite is not a new material but reaches back into ancient history. The colours are really beautiful, and soft blue-green, intense emerald green and bright cobalt blue to dark blue are the most popular shades for jewelry purposes. Hemimorphite is also found in white, colourless, brown and yellow, with the white often appearing with other colours to create a mottled look or make the colour seem pale. Well-crystallized, transparent material does occur, but it is rare and fragile. More common is the grapelike botryoidal massive form, which is found as a thick blue to blue-green crust that is translucent to opaque. Hemimorphite also occurs as a banded aggregate or mixed with dark matrix. The lustre is vitreous to silky.
Treatments and imitations
– Hemimorphite is sometimes dyed to improve or intensify the paler colours.
– Most natural hemimorphite is immersed in a very strong and permeable gluelike material to fill the hairline fractures that are nearly always found in this gemstone and to improve its stability. The process, called stabilizing or fixing, strengthens, toughens and improves the transparency of the hemimorphite, and enables lapidaries to cut larger stones. Usually, no colour is added.
– Hemimorphite could be confused with turquoise.
– This is a material that is beginning to gain more popularity. A sky-blue hemimorphite necklace appeared in one of the auctions of rare gemstone jewelry held by American auctioneers Bonhams & Butterfields.
– On the whole, hemimorphite is moderately priced, except for the pure blue material and stones in large sizes, both of which are rarer.
Working with hemimorphite
– A drusy type of hemimorphite is available. This is cut from the textured crust, its surface can be matte or crystallized and it comes in blue and blue-green colours. Drusy tends to be more delicate than material that is cut en cabochon; the crystallized or grapelike surface textures can be easily damaged if they receive an impact, and they are prone to trapping dirt and fluff, so drusy is better for earrings and pendants than for rings.
– Hemimorphite has an uneven conchoidal fracture and a perfect cleavage in one direction, making it brittle and prone to damage. It is sensitive to acids and impact, so chemical and ultrasonic cleaners should not be used. The material loses some of its water content when heated; avoid overheating the stones during polishing.
– Hemimorphite gemstones trap dirt and dust and will need cleaning with a soft toothbrush and water.