TREND GAME Staying Power Flowers continue to be perennial favorites among jewelry designers, especially in the arena of wedding jewelry. Look for oversize diamond petals haloing center stones, leafy designs on bands, and abstract flower designs in gold accented with small diamonds that offer big appeal to younger brides. Live bouquets may fade, as they say, but precious-metal flowers bloom forever.  Above: Autumn semi-mount in 18k gold with 0.32 ct. t.w. diamonds, $4,600, Erica Courtney, Los Angeles, 323-938-2373, ericacourtney.com; Florette wrap-around ring in 18k gold with