A cartilage piercing such as a helix, tragus or conch is typically pierced with a 16 gauge needle with 16 gauge initial jewellery fitted for the healing process. A piercing needle creates a slit in the skin which then creates a hole which stretches to allow space for the jewellery. If your piercing was made with a needle by a professional piercer, it's likely your piercing will be the standard 16 gauge which is common for most cartilage piercings including helix, tragus, conch, rook or forward helix.