Winner

Opi Nail Envy Soft & Thin, $15
Testers liked the way this treatment worked and how it looked. “It toughened up my nails and gave them a subtle gloss,” said one. It’s made with calcium, copper, and magnesium to harden nail protein.
To Buy: www.opi.com for locations.

Runner-Up

Barielle Nail Rebuilding Protein, $17.50
A base coat with keratin that helps build up weak nails.
To Buy: www.barielle.com.