Package from Hong Kong contained 875 pieces worth over $3.7 million.
Second-quarter sales down 44% by value.
New duties on loose polished stones and some precious-metal products will take effect mid-August.
Company posts $2.4 million deficit compared to $9.1 million for previous 12 months.
Revenue up 2% year on year for first six months.
Timepiece will go on offer for the first time in 27 years with a high estimate of $1 million.
Trade representative is carrying out three expedited investigations that might lead to new regulations at the end of this month.
Company retrieves 33,000 carats in second quarter after deposit closure earlier in the year.
Company plans to pause production at its South African deposit for two years.
Group revenue grows 32% as China and Hong Kong see strong results.