Less is the general rule, the cutout itself is already a design statement, so jewelry should support it rather than compete with it.
Match Metal to Undertone, Not Trend
Gold generally reads warmer against most skin tones under evening lighting, but the actual rule is simpler: match the metal to your other accessories so nothing looks accidental.
Body Chains for Side or Waist Cutouts
A body chain draws the eye directly to a waist or side cutout instead of competing with it the way a necklace might.
Keep Earrings as the Only Other Statement
If the dress has a bold cutout, one additional statement piece, usually earrings, is enough. Stacking a body chain, statement earrings, and a bold necklace at once pulls focus away from the dress itself.