Here's a lovely ballet certificate to print out, with "Congratulations" and blanks to fill in yourself with the details.
Ballet Certificate - Congratulations
Here's a useful printable certificate with a ballet theme and the word "Well Done". Fill in the blanks for the name of the child and what they are receiving the certificate for.
It's great to thank a special friend if they've helped you in some way, and this printable award lets you write your own message and date too - perfect as a keepsake.