events. Garnet has been developed as a U-Pb geochronometer, to date the age of crystallization as well as a thermochronometer in the (U-Th)/He system to date timing of cooling below a closure temperature. Garnets can be chemically altered and most often alter to serpentine, talc, and chlorite. Uses Gemstones Red garnets were the most commonly used gemstones in the Late Antique Roman world, and the Migration Period art of the "barbarian" peoples who took over the territory of the Western Roman Empire. They were especially used inlaid in gold cells in the cloisonné technique, a style often just called garnet cloisonné, found from Anglo-Saxon England, as at Sutton Hoo, to the Black Sea. Thousands of Tamraparniyan gold, silver and red garnet shipments were made in the old world, including to Rome, Greece, the Middle East, Serica and Anglo Saxons; recent findings such as the Staffordshire Hoard and the pendant of the Winfarthing Woman skeleton of Norfolk confirm an established gem trade route with South India and Tamraparni (ancient Sri Lanka), known from antiquity for its production of gemstones. Pure crystals of garnet are still used as gemstones. The gemstone varieties occur in shades of green, red, yellow, and orange. In the US it is known as the birthstone for January. The garnet family is one of the most complex in the gem world. It is not a single species, but is composed of multiple species and varieties. It is the state mineral of Connecticut, New York's gemstone, and star garnet (garnet with rutile asterisms) is the state gemstone of Idaho. Industrial uses Garnet sand is a good abrasive, and a common replacement for silica sand in sand blasting. Alluvial garnet grains which are rounder are more suitable for such blasting treatments. Mixed with very high pressure water, garnet is used to cut steel and other materials in water jets. For water jet cutting, garnet extracted from hard rock is suitable since it is more angular in form, therefore more efficient in cutting. Garnet paper is favored by cabinetmakers for finishing bare wood. Garnet sand is also used for water filtration media. As an abrasive, garnet can be broadly divided into two categories; blasting grade and water jet grade. The garnet, as it is mined and collected, is crushed to finer grains; all pieces which are larger than 60 mesh (250 micrometers) are normally used for sand blasting. The pieces between