Nice concept! The puzzle design is pretty good, and the character's love of diamonds is cute. Sometimes the portals didn't want to follow the mouse, had to start dragging several times. You wanted suggestions, so here's a few puzzle element ideas:
- Black hole that sucks the player in and throws him/her somewhere.
- Spring board.
- Something that pushes the diamond horizontally.
- A case/box/chest holding the diamond you have to break or unlock.
- Something that changes the angle of gravity.
- "Deadly mass" and an armor you have to wear to pass it.
- Portals with limited usage, you have to pass them a couple of times (with player or diamond).
- Liquid that passes through portals, fills canisters and pushes their weight down on a button or another element.
Other suggestions: Make the portals more animated, have them react to player/diamond passing through them. Make the world seem more alive.
Hope there's something you find useful. Feel free to implement, or ignore, any of them.