The magic is still into it, with the same diminishing return as the second bracelet.

She adds rings to the rest of her fingers. 

That's worse.

Oh well. She takes the new rings off.

...

She inspects herself in the starscape, considering the whole picture she makes instead of just individual bits. 

She turns her wings purple. 

This is a little better.

She adds gold sparkles. 

Also a little better!

Hmm. What if she turns the shaft of each feather gold?

The magic likes that.

Oh good!

She puts on dangly earrings, purple crystal with flecks of gold. 

An improvement!

Ooooh what if she makes her eyes purple with sparkly gold flecks. 

The magic thinks that is super great!

Oh cool!!!

She makes all the other purple crystals she have have gold sparkles too. 

A solid improvement. Her zaps would be real big now.

She's gonna be so great at killing swarms when she's old enough. 

She looks through the dictionary some more, and decides that while the neckline of her dress is wrong for some of the kinds of necklace, a choker or a pendant should work okay. She tries the pendant first, thin gold chain draping around her neck and down the front of her dress to end in a sparkly crystal the same purple-flecked-with-gold as the rest in a gold setting. 

The magic thinks that is a good necklace.

And if she replaces it with a purple ribbon around her neck with gold embroidery the same style as on her skirt, with the same crystal-in-setting centerpiece, is that better or worse?

A little worse.

She switches it back and looks through the book for other forms of jewelry. 

If she puts a little gold cuff with a purple-with-gold-sparkles crystal on it on her ear, does the magic like that?

Yes it does.

Yay!

What if she adds MORE of them.

She hits diminishing returns after four and it starts getting worse after eight.

She leaves it at eight. 

What if...she does the pendant AND the choker?

That's a little worse.