I made my decorative baubles in cotton sportsweight yarn, but the pattern is suitable for light DK yarn as well. Just match your hook to your yarn.
The samples were worked in Schachenmayr Catania – small amounts in assorted colours. You will need a Christmas ball - 3" in diameter (use some from last years decorations!).
You could use any 4ply/sportsweight yarn If you use a DK weight yarn (and a 3.5mm hook) you will probably eliminate the last 2 rows in order for crochet piece to fit.
Pattern gives instructions to make 2 pieces (halves) which you sew together over your ball.