Personalized pendants

My nieces' birthdays are fairly close together--one in April and one in May. When I send the girls their gifts, I usually send one package with both presents.  This year, I had big plans: I was going to make them each a sterling pendant with their name stamped into it with a crystal the color of their birthstone.  I had the plan.  I had the materials.  What I lacked, apparently, was the motivation to get both pendants done in time for the first birthday.  So I sent a gift certificate for the April birthday.  But I have siblings, and I understand the code.  I could no longer call these necklaces "birthday gifts", because I had screwed up the timeline.  I couldn't send one girl a gift certificate and the other a personalized handcrafted necklace...so now these necklaces are "just because" gifts and the May birthday girl also got a gift certificate.