Colouration can be related to several factors. Water parameters, light, the environment (substrate colour, places to hide, etc). And other fish of the same species and other species. Food can also affect colour, though less now with the good nutritional foods generally available. And of course spawning will affect colouration, as will water changes.
You don't mention the tank size, but adding another ram might be more trouble than help. Depending upon the sex of the current ram, and that of the added ram(s).