The Gold Silver ratio is at 82 right now. It would not surprise me if the arbitrage taking place in gold in advance of the Shanghai opening is the reason why gold is outperforming silver right now. Arbitrage in gold is taking place, in silver not (yet).
According to Rob Kirby the London ratio between allocated and non-allocated must be around 1:550. Any new capital that wants to be invested in gold, goes to Asia where you can still find allocated gold.
Silver will catch up at one point.