I think they look excellently drawn and they
are very difficult!
It's a choice to make them into a denser form of matter. Denser won't show through to the other side so it makes it easier to draw (less work too!). The look of a denser crystal is a foggy/glossy look.
Here's an image to show what I mean:
Dense crystalBut if you choose to make it less dense, it will be see-through and you will have to continue drawing the lights and darks you can see and what lies behind it. If you choose to do this, the crystals behind should be shaded in more than the one you're looking through. You shouldn't be able to see past 3 crystals lined together, so the third will have to take on the foggy/glossy look.
Image:
Less denseIn your image drawn so far, don't fade it entirely to white in the bottom left corner. Try to draw out the rest of the crystals in different shades of whites that has some of the beautiful cyan blue you chose, to make it darker to show their shape. The tips of each crystal can have the white glow along the top edges for some highlight points. Some white can be added to the length of each crystal as well, but not too much.
~Hope this helped! Sorry if it seems a bit confusing >.<