I would have never guessed you were using ink. Great idea. I love how you incorporate the flaw, crack, and make it a part of the piece. Wonderful. I would have never have dreamed of getting little glass balls from a scientific supply company. What a wonderful garage sale find!
I prefer the ink (basically soot and water) to petrochemically based stains. And my usual finish is a food-grade beeswax blend. I like my art to smell nice as well as look and feel nice (and sound nice, in many cases, like my gourd rattles and nuthull mini-shakers).
Glass balls are a standard laboratory item. Buying them direct from a lab supply is probably expensive, the pricing for sale to academics and corporations. I love garage sales, though you never know what you'll find.