An 11.73-carat rectangular octagonal sky blue topaz with white zircon accents in 18K yellow gold over sterling silver on an 18-inch Singapore chain creates a pendant necklace with an extraordinary amount of vivid blue: at this carat weight the sky blue topaz has enough surface area to display its clean, saturated color with full depth across the architectural rectangular octagonal faceted form. The geometric precision of the rectangular octagonal cut gives the natural topaz color maximum visibility while the octagonal clipped corners add contemporary definition. The warm gold setting creates warm-and-cool contrast that makes the sky blue appear most saturated. White zircon accents frame the topaz with sparkle that makes the blue appear richer. At 1.13 by 0.67 inches the pendant has genuine presence at the neckline. Note: no proprietary color name used.