Erica Anenberg's stylish rings are designed to fit across two fingers and come in a wide array of colors and styles. This Black Diamond Twosome Ring sells for $138 at Max & Chloe but I've seen them go for less on sites like Gilt.com, Rownine.com and ideeli.com.
Forever 21 has a much cheaper alternative. For $4.80, you can try this trend without making a big investment.
I love that brass knuckles have become a girly trend.