Step 1:
I folded wrapping paper around a 3x3 inch white paper.

Step 8:
Prefold the tip to the line indicated by the arrow.
Unfold the model afterwards.

Step 6:
Press / fold the edges downwards over the prefolded lines.

Step 11:
Fold the four edges backwards over the prefolded lines, not all edges are visible in this photo.

Step 10:
Fold the edges inwards. Use the prefolded lines as guidance, see arrows as example.

Step 9:
Prefold the four corners to the prefolded lines of step 8, see arrow as example.

Step 5:
Fold the tip upwards

Step 7:
Fold the flap downwards.
Repeat steps 4 to 7 on the backside.

Step 3:
Valley-fold over the two lines at the bottom right, then mountain-fold over the two diagonal lines. And valley-fold over the two lines at the top left.
All lines are prefolded in step 2

Step 2:
Prefold in half four times.

Step 4:
Prefold over these two lines.

Step 12:
Glue or tape the edges together.

Done!
This is a DIY video tutorial for folding the diamonds:

Photo:  Fashion, Make-up acessories, jewelry and Origami diamonds