The above image is the simple wax seal with no adornment.
The above image is the wax seal with silver highlights. The highlights are created with stamp pad pigment ink. Rub your finger across the stamp pad and then lightly rub the image on the seal.
The above image is the seal in relief with an inked background. This uses a pigment ink stamp pad as well. To accomplish this look, the brass seal is dipped onto the stamp pad and then placed in the melted wax.
The above image illustrates two techniques: highlights using PearlEx powders and wax seals with ribbon.
For my nephew's project, we used the gold background technique (next to last photo) on the outer envelope. Each "student"/guest will go to the sorting hat to get assigned to a particular house. Once assigned, they will get a scroll of assignments . At the end of the party each student will graduate and get a diploma signed by the headmaster and sealed with a ribbon.