Translations for crystal in French

Here are paragraphs from public domain books translated:

As to Porthos, except his real name (as was the case with those of his two comrades), his life was very easily known. Vain and indiscreet, it was as easy to see through him as through a crystal. The only thing to mislead the investigator would have been belief in all the good things he said of himself.	Quant à Porthos, excepté son véritable nom, que M. de Tréville savait seul, ainsi que celui de ses deux camarades, sa vie était facile à connaître. Vaniteux et indiscret, on voyait à travers lui comme à travers un cristal. La seule chose qui eût pu égarer l’investigateur eût été que l’on eût cru tout le bien qu’il disait de lui.
The Three Musketeers, by Alexandre Dumas	Les Trois Mousquetaires, de Alexandre Dumas