I had a jeweler who did this, quite smart and exciting.
When they finished a custom piece took a picture of the piece. Any
office supply store has print your own business cards. They made
their own but for their LOGO they printed a dozen cards with the
customers new ring on it instead.
Then when they delivered the piece they said "Glad you love your
ring. We live by referrals, would you mind giving our cards to your
Response? "sure, be glad to"
Then they see THEIR ring on the cards. of course they give them out!