Like other pearl types, black pearls follow the GIA pearl grading scale of size, shape, luster, color, matching (or craftsmanship), surface quality, and nacre. The best quality pearls will be perfectly round with smooth, unblemished surfaces, intense and eye-catching colors, and sharp, high-contrast reflections. Pearls that display all of these things equally will be priced according to size; large, high quality pearls will be more valuable than smaller ones. However, a flawless, top quality pearl of a smaller size will almost always be more valuable than a larger one of low quality.