Irene Neuwirth’s colorful gems and aw-shucks demeanor charm celebs and real folks alike. Read the full story.    18k rose gold pendant necklace with 18.06 cts. t.w. boulder opals, 4.88 cts. t.w. Lightning Ridge opals, and 0.2 ct. t.w. diamond pavé; $22,500; Irene Neuwirth, Venice, Calif.; 310-450-6063; ireneneuwirth.com18k rose gold ring with 5.79 ct. opal heart and 0.12 ct. t.w. diamond pavé; $8,120 18k yellow gold necklace with 247.25 cts. t.w. turquoise and 0.88 ct. t.w. diamond pavé; $32,480 18k rose gold ring with 2.24 ct. rose-cut diamond and 1.39 cts. t.w. diamond pavé; price on request18k yellow gold earrings with 5.39 cts. t.w. Lightning Ridge opals, 65.84 cts. t.w. Kingman turquoise drops, and 0.66 ct. t.w. diamond pavé; $21,56018k white and yellow gold necklace with 59.79 ct. opal, 36.14 cts. t.w. indicolite, 5.16 cts. t.w. rose-cut diamonds, an