agate alloy aluminium amber american platinum eagle amethyst aquamarine art asymptote australia australian gold nugget austria aventurine brass bronze bullion coin canada canadian gold maple leaf carnelian chemical element china citrine coin commodity commodity market copal copper crown gold crown jewels currency diamond double eagle ductility economics electrum emerald face value france garnet gemstone gold gold as an investment gold coin gold nugget hallmark inflation ingot iridium jade jasper jewellery johnson matthey krugerrand lapis lazuli legal tender malachite market value melting point metal money napoleon iii of france noble metal onyx opal ore osmium palladium palladium as an investment pearl peridot platinum platinum as an investment platinum group quartz reactivity rhodium royal canadian mint ruby ruthenium sapphire silver silver as an investment silver coin sodalite south africa stainless steel sterling silver store of value sunstone tanzanite taxation of precious metals topaz troy weight united states dollar washington monument