Ref. No. 1024/41-219
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
The Muslim brother should sell the precious stone received as a guarantee and keep only as much money as the non-Muslim owed to him i.e. 10000 USD only. The rest amount of 90,000 USD must be returned to the non-Muslim brother. The non-Muslim brother is the owner of extra amount of 90,000. So it is forbidden and haram as per Shariah for a Muslim to take extra amount.
And Allah knows best
Darul Uloom Waqf Deoband