Expect the Unexpected, page-110

Not sure where you're getting your logic from but it's most definitely flawed, no offense but your SP evaluation is ridiculously under valued based on your avg. price per carat(which is overvalued)

-avg. All Ords PE is above 15, so why not use 15 here

NPAT x PE ÷ SOI = SP
$8m x 15 ÷ 620,695,864 = 19.5 cents(rounded)

-MUS would only need just above $8m profit(not revenue) from the auction to sustain a SP of 19.5cents, we don't all know the exact opex or the result of the coming auction but it's pretty safe to say that it's going to be goodbye to the SP in the teens post auction.
-another factor that needs to be taken into consideration is that the market is forward thinking, and with 2 auctions planned next year you can bet the market will start to take this into consideration after the first auction

For example let's say MUS pull $35m.aud(probably the conservative average estimation) and after all costs(etc) end up with say $15m NPAT, well using avg. All Ords PE that would give a SP of 36cents, even with a more conservative PE of 10 the SP would be 24cents, now more than double those SP figures as the market starts to factor in 2 more coming ruby auctions, and then there's the graphite jorc along with other news that will also eventually be factored into the SP. This is by no means a thorough examination of the the companies opex/capex etc, but just a back of the envelope estimation.

Just for the fun of it, gettting back to your over evaluation of $120m from the auction, well run the basic numbers on that. Let's say that only $60m was profit and use a conservative PE of 10:
$60m x 10 ÷ 620,695,864 = 97 cents(rounded).....but let's forget about that SP for the moment(maybe in 2018 or 2019)

All up, I reckon 18cents will be min pre-auction and 20+cents min post-auction, and then to slowly creep up to a min of 35cents by early next year as market starts to factor in increased production, 2 auctions and graphite. In terms of upper SP levels well I wouldn't be at all surprised to see MUS hit 50+cents next year if management can stick to the plan.