Did anyone have any success in contacting the seller of that book on Indian coins? I tried but got no reply.

To be a perfect pedant about this, in the article "Numismatic Vocabulary: What's the Differents?" from last week's E-Sylum, the word "different" (or plural "differents") should be spelled différent (or différents), and pronounced accordingly. Différent in French is ordinarily an adjective not a noun, and as an adjective it does translate as "different." However, as a noun to indicate the name of an engraver, such a translation will clearly not do.