Carats:

Carats are a weight measurement based on grams for diamonds and other gemstones. The higher the carat count, the more expensive the rock, especially in regards to precious stones.

Carrots:

A pointy root vegetable, usually orange, although they can be other colors. Carrots are crunchy, delicious and improve your night vision. But they have absolutely nothing to do with rings.

Karats:

Karat (singular) is a purity measurement for GOLD. 24k is 100% pure, but too soft for jewelry. It must be alloyed with another metal. 14k Gold is most common. 18k and 10k are also popular. Higher Karat count = higher price point.