Persuading bead fans to buy more sophisticated pieces of silver requires a skillful way with words, say retail sales pros. Maneuver with discretion, pay attention to customers' clothes, and never stop selling! Read the full story.    Photograph by Greg Sorensen. Styling by Brooke Magnaghi. Market editor: Jennifer Heebner; makeup by Rebecca Casciano for LVA Artists; hair by Gusléne Bubak; manicure by Joi Offutt; sweater: Kim HallerEarrings in silver and 14k gold with green jade, $1,295, Anthony Camargo at Fragments, NYC, 212-226-8878, fragments.com; Aria waterfall necklace in silver and 14k gold with diamonds, $2,600, Mabel Chong, San Francisco, 415-885-0198, mabelchong.com; skull ring in silver with diamonds, $4,500, Jessica Kagan Cushman at Fragments, NYC, 212-226-8878, jessicacushman.com; cuff in silv