Not sure if this meditation is mentioned here before, but if you hold a crystal in your hands or on a particular place on your body, like a chakra you can imagine that you shrink to the size of the crystal and enter it. Could be a good idea to look for cracks etc in the gem before you start, then it will be easier to imagine it. Then just let your imagination run free.
You can also place a hematite or some other grounding stone under your feet whilst doing this so your imagery gets more concrete.

I have done this with some crystals and it is a very cool experience. I once had a rose quarts on my heart and inside the stone I saw my grandparents that have past away, and I saw a lot of other people I love and care about and it was a really strong experience, I felt so much love in there:)

I have had experience with quartz points using six pieces formed in a triangle around me while sitting with legs straight out. Put the pieces  together point to other end in a v shape in three sets of two. It was an amazing meditation, very energising.

I first saw that technique discussed in a crystal book by Uma Silbey. I never would have thought to try that. Quartz has a very pleasant, cool sensation when you direct your consciousness into it.

That was a wonderful experience with the rose quartz!