Choose a heavier gauge headpin when making a simple loop. To ensure the loop holds up to wear and tear, we recommend 0.028-inch 21-gauge headpins. They are a heavy gauge wire, but the crystals will fit fine.
When finishing with a wrapped loop we recommend using 0.016-inch 26-gauge headpins or 0.02-inch 24-gauge headpins. The finer wire will yield a nice finish when wrapped and it will remain secure through years of wear; the crystals will also fit on this gauge wire.