The two reports we have had from MUS on the recovery rate is that it is around 0.3 carats per ton. On a 1050 tonnes a day (capacity if they run two shifts) this is around 300 carats a day. Using your assumption of US$350 a carat that is A$140,000 a day!
Even if you take your 250T a day rate for which we have no reason to think is reasonable, the annual production would be 27,000 carats @ US$350 = A$12.75 million. Assuming that MUS keeps half the production then it is hard to come up with any valuation where MUS is only worth $7.9 million.
Yes the mine is not JORC compliant, but from the sampling they have done so far the resource appears quite large. They have water on site and the geology to build the required storage and tailing dams. I really struggle to find a reason for the current SP other than the market thinks MUS is outright lying.
MUS Price at posting:
2.6¢ Sentiment: Buy Disclosure: Held