Thai baht of weight for precious metals and gemstones. One baht = 15.244 grams. Since the standard purity of Thai gold is 96.5 percent, the actual gold content of one baht by weight is 15.244 × 0.965 = 14.71046 grams; equivalent to about 0.473 troy ounces. 15.244 grams is used for bullion; in the case of jewellery, one baht should be more than 15.16 grams. The Bank of Thailand adopted a series of exchange controls on 19 December 2006, which resulted in a significant divergence between offshore and onshore exchange rates, with spreads of up to 10 percent between the two markets.
Metallurgical assay on the composition of the rock in which the precious metals are concentrated, and in many laboratories an empirical approach based on long experience is used. A complex reaction takes place, whereby the carbon source reduces the lead oxide to lead, which alloys with the precious metals: at the same time, the fluxes combine with the crushed rock, reducing its melting point and forming a glassy slag. When fusion is complete, the sample is tipped into a mold (usually iron) where the slag floats to the top, and the lead, now alloyed with the precious metals, sinks to the bottom,