Agate is formed in multi-colored concentric layers. No two agates are quite the same. Agate is classified as a banded chalcedony or micro-crystalline quartz. The individual bands or layers give this gemstone its uniqueness and character.
The layered agate material used in producing cameo gem carvings is usually cut from agates with even parallel layers, a lighter layer above a darker one. The agate used in today's cameos is naturally multiple shades of grey in color, ranging from a milky white translucent to dark grey. The lower and softer layer is dyed to produce the highly desirable blue chalcedony color, while the harder, lighter colored upper layer does not accept dying and remains white or milky in appearance.
Only two percent of all mined agate material is of a quality suitable for detailed cameo cutting, and only a small percentage of that material can be dyed blue, lending rarity to precious cameos (orange-red cameos are carved from carnelian, another form of chalcedony; see below).
The exquisite motifs and silhouettes featured in our cameo offerings have been carved relief-style, employing the use of a highly sophisticated ultrasonic etching process, and then are elegantly framed in traditional and modern designs.
Agate has a Mohs hardness rating of 6.5-7. Petrified wood is also a form of agate.