Garnet forms a large, diverse family of silicate minerals. Many of its subspecies are used in jewellery. People have been using it as a gemstone since the Bronze Age, although mostly in its red, Pyrope/Almandine variety.
Today we know that garnets can come in red, purple, orange, yellow, green, brown, black, iridescent and even blue. Its price depends mainly on the colour. While dark red stones are relatively cheap, others, like emerald-green Tsavorite or a strong orange Spessartine, can get quite pricey.
Most garnets come from Eastern Africa, Madagascar, Sri Lanka, USA and Burma. Garnet enjoyed wide market expansion in the last century, after new, attractive varieties were discovered.
Starting with 1967 discovery of Tsavorite, named after Tsavo region of Kenya. Which remains sole source of gem grade material until now.
In 1991 Spessartine or Spessartite (US) entered the commercial market, after large deposits discovery in Africa. It was already known and named after Spessart region in Bavaria, Germany but was not available in commercial quantity before African deposits were revealed.
Later on, first examples of colour changing blue garnet were discovered in 1998 in Madagascar. It remains extremely rare to this day and more of a collector stone with record 4.2 carat gem sold in 2003 for 6.8 million USD.