Here is an official letter from Hipshot of SASS.

SASS ®

Single Action Shooting Society 215 Cowboy Way.

Edgewood, New Mexico 87015

(505) 843-1320, Fax (505) 843-1333

March 23, 2014

SNS Casting

Dear Jim and Ryan:

"  Revolver and rifle ammunition may not be jacketed, semi-jacketed, plated, gas checked, or copper washed. It must be all lead. molydisulfide, polymer coated bullets, or equivalent are acceptable." Shooters Handbook 2014 p.12

There is no mention of color, therefore:

Anyone using a METALLIC-colored (gold, brass, copper, silver, &tc) coated bullet would be subject to inspection at the loading table to insure that he/she are not using plated/jacketed ammo... 

Hipshot  SASS#7