I know that distance Reiki attunements work as well as those done in person. Regarding the stones, no stone so far has asked that I go through any special process to work with them in person or across distance and/or time. Ask and trust. If the stone recommends waiting, wait. If not, enjoy. An experience across time and/or distance can be even more powerful than one where a physically present coworker can distract us.
This said, stones can easily attune us if we would like that! Same goes: ask 'em. In my experience, an attunement is simply the energetic transfer of a skill. We tend to think of spiritual--inner--gifts, but we should be able do that with anything, if both giver and receiver are open to it. It's a long-forgotten way, that seems to be coming back into our awareness.
We've been talking about diamonds elsewhere, and my funds need to go in other directions right now. Maybe I'll ask a diamond for an attunement to diamond skills, or presence? If I do, I'll report the results. If you try this with a stone, maybe come back and tell us? If nothing happens, that's a result too! In that case, maybe some stone wants to work in person?