On the eve of the Tucson gem shows, the market is more mercurial than everAttention in the colored stone market has turned toward Tucson. Dealers have mixed predictions about the show. Many dealers report that the holiday was, at press time, softer than anticipated for the gem and jewelry industry. The sales activity at Tucson tends to be strong if Christmas sales were good, because retailers are far more open to buying for stock if they had a good season. On the flip side, caution prevails if the holiday was slow.As far as trends go, solitaire diamond earrings have been stronger than anticipated. The popular sizes included 1 ct. and 1.50 cts. t.w. Earrings featuring black diamonds reportedly sold well, as did classic anniversary bands.In colored stones, blue sapphire, aquamarine, and tanzanite are always good sellers for retailers. Emerald sales have also been good in both the high-end