3.1. Series I (BCR 1, BCR2 and BCR 3)
According to Series I, the highest lead concentrations leached from treated ruby seems to be extracted from BCR 2 (reduction step) except samples from factories 5 and 6 which BCR 3 gave more effect. The amounts of lead extracted from each step agreed well with the gemmological appearance which number of cracks was clearly appeared after passing BCR 2.