Thank you very much Jamey. I discovered yesterday that a long strand of small turquoise,-bought from a Tibetan dealer-, most probably is coloured. sigh.... I' ll take a hammer one of these days and break several beads and test thus the different shades of turquoise.
I'll take pictures and post them.
In the meantime I'll try to focus on the beads I'm quite sure are uncoloured. Every little bit helps :-)
Happy holidays everyone!