Your story is hard to understand because you said you want treasures from the ocean like rings and suddenly your friend went to you going for rocks.

Universal scuba dive rule almost anywhere is to leave everything where you found it. Especially anything natural, regardless of it being organic or not. If you choose to disregard this, that’s your choice. But to try to “rationalize” why it’s okay is just mental Gymnastics. Law is the law, it’s not ethics, but in this case it’s against both. So Don’t do it at all, OR “just do it”*** if you’re gonna do it anyway, as oppose to trying to work your mind into finding why the law is flawed or not flawed or the ethical disdain toward it leaves loops holes to be exploited. It really is on you

Rocks and sand advertised to be procured in Hawaii ARE actually ILLEGAL to sell in Hawaii, as with intentional procurement. Of course you can sell legally sell “sand”. But you would have to have collected it elsewhere.

It doesn’t even have to be Hawaiian sand. You can call the cops on a store that sells sand in bottles and has a sign that says “Natural sand from Hawaiian beaches!” Even though it’s sand from China. The sign is illegal

Sand on sandals (slippahs, in Hawaiia) aren’t intentional procurement. Basically the law is trying to say don’t be a dick.