How to make a diamond origami envelope

(page 4)

5th picture of diamond origami envelope

05.

Apply the vertical "gate-fold" of the step #4 and then unfold.

Prepare to apply four horizontal valley-folds and then unfold.

6th picture of diamond origami envelope

06.

Apply four horizontal valley-folds of the step #5 and then unfold.

Prepare to apply four vertical valley-folds and then unfold.