Translations for purity in French

Here are paragraphs from public domain books translated:

At that moment he finished pushing back the silk cord and, from the hollow of a cup he took between his thumb and forefinger a wonderful blue stone, perfect in respect of size and purity.	Au même instant, il achevait d’écarter les cordonnets de soie, et, au creux d’une olive, il saisissait entre le pouce et l’index une admirable pierre bleue, d’une pureté et d’une taille parfaites.
The Confessions of Arsene Lupin, by Maurice Leblanc	Les Confidences d’Arsène Lupin, de Maurice Leblanc