This is one of a reliable PM sector Bullish/bearish indicator.

This ratio lead the buy signal back in Jan 2016 and rang the bell at the final bottom in PM sector.

It also gave signal for this long correction at the top in July with RSI as high as 1987 above 80 showing divergence with price.

Currently it gave signal on Dec 21 that correction is over by once again RSI bouncing off its Head and shoulder neckline ( BT ).
By the time the ratio crosses July high level PM sector stocks will have moved much higher. IMHO!!!