For best results, do steps 1 through 4 one day in advance.

One day in advance, bake cookies. Prepare cookie dough following recipe instructions. Roll dough to 1/8 in. thickness. Using diamond template and “C”, “D” and “E” star cut-outs, cut cookies. Bake and cool.

Prepare royal icing. Prepare royal icing following recipe instructions.

Outline diamond cookies. Using decorating bag with tip 3 and full-strength icing, pipe outline on diamond cookies. Reserve ¼ cup full-strength icing.

Fill in star cookies. Thin half remaining icing to count of 15 according to package instructions. Pour into decorating bag. Cut ¼ in. tip in bag. Flow thinned icing to within 1/8 in. of edge of star cookies; fill in. Let dry overnight.

Thin other half remaining icing to count of 10 according to package instructions. Pour into decorating bag. Cut ¼ in. tip in bag. Flow thinned icing to fill diamond cookies. Let dry 6 to 8 hours or overnight.

Decorate gem cookies. Prepare decorating bag with tip 3 and reserved ¼ cup full-strength icing. Pipe gem lines on top of dried icing. Let dry, about 1 to 2 hours. Using decorating brush, paint gold metallic paint over gem lines. Let dry, about 5 to 10 minutes.

Decorate star cookies. Using decorating brush, paint gold metallic paint over entire iced cookie. Let dry, about 5 to 10 minutes.