Gemstones include high-quality emerald, lapis lazuli, red garnet and ruby. Pure crystals of garnet are still used as gemstones. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Almandine has nicknames of Oriental garnet, almandine ruby, and carbuncle. Yttrium aluminium garnet (YAG), YAl(AlO), is used for synthetic gemstones. Almandine is an iron alumina garnet, of deep red color, inclining to purple. Status in jewellery is reflected in size, intricacy, and use of gold, silver and garnet. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry. The university's colors are garnet and gold. Yttrium iron garnet (YIG) spheres can act as tunable microwave resonators. The colors of garnet and gold represent a merging of the university's past. Garnet group minerals occur in different rock types. Spessartine or spessartite is manganese aluminium garnet, MnAl(SiO). Lutetium aluminium garnet (LuAG) is used as a phosphor in LED light bulbs.