"I think that's it! This is really amazing - be careful, but I really hope it works out for you."

"Thanks! I'll be super careful and hopefully we'll both make good money." 

She heads off, skipping occasionally, and goes home to relax in fullform for a while before she sleeps.

The following afternoon she races through her homework and sets to enchanting again, starting with a twist tie bent into a circle. If she changes "holder" to "wearer" in the incantation, does it then only work when it's on a finger?

It will also work on a toe or with some of her hair threaded through it or if attached to her clothes, but not in a pocket or held in her hand.

Huh, she had not expected the clothes thing to work. Very convenient, though, means pretty much any body configuration should be able to use one. Next test: squashing it out of shape but not untwisting it. This is done gingerly and at arm's length, in case disenchanting a thing makes it catch fire or something.

It doesn't catch fire. It is harder to wear in this form but when she manages it, it still works.

She straightens it out, untwists the ring, and retwists it again.

It continues to work through these perturbations.

And if she cuts through the wire at the opposite side from where the ends twine together, and retwists the cut ends into a slightly smaller but still serviceable ring?

That doesn't work anymore.

But it didn't explode in her face, either. She should probably still offer extra durability for cheap, in case not exploding is a dragon thing. Does it start working again if she re-enchants it?

Yes, it reenchants just fine.

Excellent. She enchants the copper-and-amethyst ring, checks for completeness that it works like the twist tie did.

It works just the same.

She tries the following things in order until one of them changes the behavior of the spell.

* bending one of the little sticking-out wire ends

* clipping off a little bit of one of the sticking-out wire ends

* unwinding the wire from around the rock partway

* unwinding the wire from around the rock the rest of the way

* putting the rock back in (though less elegantly then Brenda did it)

Clipping off a bit breaks the enchantment.

Current working hypothesis: anything that makes it cease to be one object breaks the enchantment. She re-enchants it and continues down the list.

Unwinding doesn't disenchant the object till the rock comes off. Putting it back on doesn't reenchant it.

Re-enchant again and

* scratch the rock a bit

* crush a bit of the wire between pliers so it has little marks on it

Scratching has the first really interesting result - the enchantment glitches, turning her invisible and then failing, then turning just the arm on which she's wearing the ring invisible but fading back in at the shoulder; then it turns her invisible and seems to hold, but only a few minutes, before it flickers off again.

Seeing one arm go invisible but not the rest of her draws an "Ack!". Once it seems to have settled on "off" she takes the rock out again to break the enchantment. Does it still disenchant and re-enchant normally?

This works as expected.

Her notes now include "consider rings with small/no stones" and "re-enchantment warranty??". She moves on to crunching up the wire a little.

That works about like scratching the rock, though this time more of her is invisible when it flickers through a partial.

Disenchant, reenchant, all those invisibility diagrams she made a few weeks ago are really coming in handy now. Next test: normal wear and tear. She wears the ring while she does her homework the next evening, not being particularly careful with it but not deliberately whacking it on anything either. Assuming this doesn't break it, she idly fidgets with it on the table for a while, spinning it and flicking it back and forth and suchlike.

It doesn't break while worn or fidgeted with.