Earstretching.net

Dead-stretching is fine if your ears are 100% ready to stretch. I dead-stretched to 2G and to 1G and it barely even felt like a stretch because I'd stayed at the previous size for so long. But you should never force jewelry in or stretch with silicone. Silicone expands inside your ear so it'll expand the hole whether you're ready for it or not, and it's bad for fresh stretches anyway.

why avoid clay?

Super porous.
Actual clay/ceramic dust is carcogenic. And polymer clays aren't suitable for skin. Most sealant & varnishes aren't either, and do they do rub off over time. As are some glass glazes/finishes

Wear it through earskins if you must.