Looks like you have 4 of the 1983 (ND) Saudi 500 riyal banknotes. The catalog number is P-26
N#216661
http://banknote.ws/COLLECTION/countries/ASI/SAR/SAR0026.htm
There are several varieties that differ by spelling and notation of signatures. You have at least 2 varieties based on the pictures you uploaded.
These notes MIGHT be worth about US$200 each. I see a recent auction on ebay where one similar note in XF condition sold in Canada for about that amount.
You should take your notes to a trustworthy banknote dealer. Do NOT send them by mail. They will get "lost" in India's mail system.
Good luck my friend~
PS: most banknotes are worth only a few dollars. I don't know where you got your banknotes and I can't say whether your banknotes are real. I hope they are real and I hope they are very valuable! But be careful. They need to be authenticated by someone you trust.