I've always known the white ones work, but we didn't happen to have any so I swiped some orange ones from SO's old golf bag. They work too! New young pullet spent about an hour clucking all over the place--in the coop, under the nest box, on top of the waterer--before she finally laid her first egg right next to the orange golf ball in the middle of an empty nest!
So in case you were wondering, orange does work too!
So in case you were wondering, orange does work too!