You can look at the old bear catalogs and see a year where to riser wood was listed as a particular wood, and then find bows from that year with various riser woods. I think they used the standard material and color for that year but if they ran out they would not stop production if a substitute material is available. Thes become more collectable. The oddballs.
Ask Rich Lopez about the 1966 Kodiak with red phenolic riser and rosewood caps. Looks like a '68 Super Kodiak but red. Only one made. What would you say that sucker is worth. I saw it on *bay several years ago for sale by the original owner and how he came by it. It went for bigger bucks than I was willing to pay. It had an "X" in the serial number - "Experimental"