Asbestos insulation work is the big one. They used to handle that stuff with bare hands and no masks. Glad that's over.

Ugh, my first tries always look like abstract art!

Calling the glass trick 'old as dirt' isn't really fair because it's still the most common scam I see. Besides a loupe, I use a cheap polariscope to check for double refraction, which glass doesn't have. That local guy was probably just clueless, they often are. For Mumbai, you find real dealers by asking for family-run shops that have been there for decades, not the new ones.