Chalcedony

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Victorian Scottish Agate Brooch.

Chalcedony is cryptocrystalline quartz. It is semitransparent to opaque and, depending on it's color, the chalcedony is further divided in several varieties.

History

All varieties of chalcedony were very popular in Victorian jewelry. Moss agate, known for its green tree-like patterns was a particular favorite. Bloodstone was often used for cameos and intaglios for gentleman's jewelry. Carnelian, also popular for intaglios, is often found in beads from the Victorian Era. Banded stones like sardonyx and onyx were used extensively for cameos and some of the most interesting beads feature banded agate. The term "hardstone" used in reference to a cameo usually refers to some form of chalcedony.

Victorian Era Scottish jewelry features many and varied combinations of chalcedony cut en cabochon and faceted sent in silver and sometimes gold. Often the pieces are fitted together mosaic style. Scottish agate or pebble jewelry as it is sometimes called, became fashionable after Victoria bought Balmoral Castle in 1848.

Chalcedony Varities
Agate Various Colors, Banded or Interwoven
Bloodstone Dark Green with Red Spots
Carnelian Orangish to Brownish Red
Chrysocolla Light Blue or Blue-Green
Chrysoprase apple green
Fire Agate Brown with Multicolor Iridescence
Jasper All Colors Except Black
Onyx Black & White
Petrified Wood Multicolored Silicified Wood
Prase Dull Green
Sardonyx Brownish Red & White
Sard Brownish Red to Orange

Gemological Information

Gemological information for chalcedony
Color All colors
Crystal structure Trigonal (polycrystalline quartz)
Family Quartz
Refractive index ~1.54
Durability Very durable
Hardness 7
Treatments Dying
Country of origin World wide deposits
Chalcedony care
Ultrasonic cleaning Usually safe
Steam cleaning Usually safe
Warm soapy water Safe
Chemical attack Avoid
Light sensitivity Stable (unless dyed)
Lang Antiques
Lang Antiques