There are pictures of my ball necklaces here on my main blog.
What I did was
Round 1) Ch4, join to make a ring and work 6dc into the centre - join by making a sl st into the first dc
Round 2) (Increase round) Work 2dc into each dc - join
Round 3) Dc into each dc of previous round. Join
Round 4) (Decrease) Work dc2tog all round. Join
Leave a tail and fasten off.
Turn it inside out and stuff it with leftover yarn to make it as hard or soft as you want and use the tail to close the end.
In fact after a while I changed step 1 and instead of the initial crochet chain I started with a “loop” ring which can be pulled completely closed. Debbie Stoller in "The Happy Hooker" calls this the “adjustable” or magic ring method and the best I can do is to refer you to her excellent description.
My smaller beads I made with 4 or 5 dc into the ring and the larger ones with 6-8dc. Then I threaded them onto ribbon with knots between each.
PS I have used UK crochet abbreviations - I know the US ones are different.