Learn Turkish: Elmas, parıltı ve berraklık açısından çok değerli. - The diamond is very valuable in terms of sparkle and clarity.

Açısından is built from açı (angle or perspective), the possessive suffix -sı, the buffer letter -n-, and the ablative suffix -dan (from). Literally, it means "from the angle of." It is used with bare nouns to mean "in terms of."

Why is there only one açısından if it applies to both parıltı and berraklık?

In Turkish, when you connect nouns with ve (and), you only need to add the postposition to the final noun in the list. It automatically applies to the whole group, so parıltı ve berraklık açısından means "in terms of sparkle and clarity."

Could I use bakımından instead of açısından here?

Yes, absolutely. Bakımından and açısından are virtually interchangeable when talking about evaluation or perspective. Parıltı ve berraklık bakımından would also mean "in terms of sparkle and clarity."

I know berrak means clear. How does the -lık suffix change it here?

The -lık (or -lik, -luk, -lük) suffix turns the adjective berrak (clear/limpid) into the abstract noun berraklık (clarity). It functions just like the English suffixes "-ness" or "-ity."