HOT STOCK TIP Stud Finder Melissa Joy Manning’s Rock Candy line of stud earrings celebrates one-off rough cuts of gemstones. Choose from 44 SKUs—in 14k recycled gold, featuring her signature wraparound hug prongs, bezel settings, and stick silhouettes—with sapphire, tourmaline, topaz, garnet, aquamarine, and sunstone, among other gems.     CAN’T-MISS COLLECTION Rainbow Connection­ Bella Campbell’s 30-year love affair with color has paved the way for the Campbellian Collection, celebrating rare gems and one-of-a-kind stones. Since debuting her line last fall, Campbell, a former stone seller for Kaiser Gems, has racked up four AGTA Spectrum Awards. Earrings in 18k gold with 5 cts. t.w. orange and red spinel centers, 4 cts. t.w. hot pink spinels, and 0.65 ct. t.w. diamonds; $21,400; Campbellian Collection, NYC; 908-656-5614; camp