Metals are traded against the US dollar (USD) and, like standard Forex trades, are presented in pairs, as follows:
Gold = XAUUSD
Silver = XAGUSD
Platinum = XPTUSD
Gold vs. Australian Dollar = XAUAUD
Gold vs. Swiss Franc = XAUCHF
Gold vs. Euro = XAUEUR
Gold vs. Great Britain Pound = XAUGBP