Q:
A: I think you have to fingerspell that one. If you know anyone who uses Indian Sign Language, they might have a sign for "diwali" in that language. In which case, you would fingerspell "diwali", then provide the Indian sign, then continue using the Indian sign without fingerspelling. Ethnic words, like names of countries or certain holidays can be signed using words from the native sign language of that country. If worse comes to worse, and you can't find a sign for diwali, but you don't want to fingerspell it every time, then fingerspell it, give an initialized sign, then just used the initialized sign from there on. Also, you could just fingerspell diwali, describe it as a "Indian celebration" or "light celebration", then just use the phrase "Indian celebration" or "light celebration" from there on.