All normal boas are Tyrosinase Positive. Tyrosinase is an enzyme that produces melanin, and other darker pigments. In "T Albinos" the black areas are typical purplish/brownish, or lavender. I assume this is because the melanin(black) got knocked out, but other pigments produced by tyrosinase still remain. In the T- albinos the black areas are typically white. T albinos are sometimes referred to as lavender, or lavender albino, but this varies from species to species.