The classic undertone test: look at your wrist veins in daylight. Blue-purple veins suggest cool undertones — silver, white gold, and platinum will flatter. Green veins suggest warm undertones — yellow and rose gold glow on you. Both? You're neutral and can wear anything.
The better test
Wardrobe beats veins: if your closet leans black, navy, and jewel tones, white metals integrate seamlessly; camel, cream, and earth tones call for yellow gold. And the modern answer is mixing — a two-tone stack solves the question permanently.