The carrier oil used will effect end color in more ways than one. First some have slightly yellowish tints. Second the carrier oil (I believe it is the oil that does this but I could be wrong it might be the bb or the hormone itself) will slightly oxidize during the brewing process. I myself have been playing with an oil based winny brew the past week. And it started clear and by the time I got it to hold it almost looks like a tren. It is from the oil oxidizing. I don't think it would hurt you but I wouldn't use anything that is like brown or too dark.
Think about the oil on your car. It starts looking like honey then can end up dark brown. Now that is from contaminates. There is a guy on youtube that just does home self testing of different products. One of his tests was different car oils. He just put X amount in a glass coffee pot the heated it at whatever temp for so long. Now that oil ended up getting darker and not from contaminates, from oxidizing due to the heat. So I am fairly sure we can have similar situations with our brews, depending on how high and long we heat them.
So a slight yellowing of the brew is probably the earliest sign of the oil starting to oxidize. That is if it is from the oil and not from the raw powder being yellowish to begin with.
We typically only think of tren being that amber color and for the most parts it usually is the only one but if you have something like test cypionate that needs a little more heat to brew and hold then there is going to be some oxidizing. It could be to the hormone itself but I think it is to the oil. I also seem to remember that some test cyp powder actually has a slight yellowish tint to it, or am I confusing that with somet else?
I will say that I didn't really notice a distinguishable difference in color after I filtered it.
