In Oman the silversmith has three sources of top quality silver with which to make Khanjars.
1. Silver ingots imported from China. The Omani mine at Sohar (MEGAN)also produces silver Ingots as a bi product of its copper mining.
2. Scrap silver ( when a lady dies it is usual for her dowry silver to be sold back to the silver smith and melted for essentially the next requirement for a silver Dowry.
3. Maria Theresa Thalers. She was ruler of Austria and Spain and her coins are commemorative dated 1780 when she died and continue to be highly respected for silver content even today. see below and also note the website among many with additional detail on this coinage>
http://www.theresia.name/en/