Oh, please don't make me go through this again...
No, it is not possible to short sell the pink beauties through traditional brokerage accounts. However, there is no rule that stipulates a short seller must run his trades through a traditional brokerage account. If you can find the suckers, you can go off-exchange and do almost anything you like.
For what it's worth, I did try with CMKM Diamonds, albeit half-heartedly, but was never able to find a contra-party who was serious about owning a significant amount of their stock.
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