Platinum has had a sharp rally in recent sessions, while gold has been only slightly higher, bringing the two heavier precious metals (specific gravity of 19.30 for Au and 21.45 for Pt) to parity for the first time since April. The ratio remains high, and has been elevated since gold left the more-industrial platinum in the dust in the summer of 2011:

This has been one of the longer periods of inversion in recent history. Selling gold and buying platinum in equal weights when the ratio is well over 1.0 has been a dependable money-maker for patient traders, as the ratio tends to revert to well under 1.0.