Red Jasper

Jasper occurs in extensive beds of sedimentary or metamorphic origin, is typically associated with banded iron formations, and also forms cavity fillings, nodules or veins in iron ores and altered igneous rocks; red to brown jasper can also be the petrifying material in fossil wood. Jaspers are found worldwide, with particular colors or patterns tied to particular localities.

Red jasper is opaque with a waxy to dull luster, unlike translucent agate; its refractive index (about 1.54) and specific gravity (about 2.6) are those of quartz. Jasper is commonly dyed, which can be detected by appearance, absorption spectrum or a Chelsea filter, and heating, which changes its color and is undetectable. Mindat warns that the word jasper is also used informally for many other opaque lapidary materials, including some igneous and sedimentary rocks, so a trade name containing "jasper" does not by itself prove the stone is jasper.

The International Gem Society describes all types of jasper as trouble free to care for and hardy enough for all jewelry uses, with excellent wearability; it takes an excellent polish and is usually cut as cabochons, beads or carvings.

The name jasper comes from the Greek for "spotted stone". The International Gem Society notes that the use of jaspers in jewelry goes back into the early history of civilization.