Hephaestus

When Hulga decides to change her name from Joy to Hulga, the following happens:

She had a vision of the name working like the ugly sweating Vulcan who stayed in the furnace and to whom, presumably the goddess had to come when called. She saw it as the name of her highest creative act. (16)

The "Ugly sweating Vulcan" that Hulga imagines was a Roman god, adapted from the Greek god Hephaestus, who's the god of fire, blacksmiths, stonemasons, and more. So right away, we can see her name change—via the Vulcan reference, and because the narrator comes right out and says as much—as an act of fiery creation. Which means it's a big deal. She isn't forging a basket, she's forging herself. Later in the same paragraph we're told:

One of her major triumphs was that her mother had not been able to turn her dust into Joy, but the greater one was that she had been able to turn it herself into Hulga. (16)

So yeah: Hulga is wresting her person away from her mother. And you know what? Hephaestus had a limp—a.k.a. a problem with his leg, just like someone we know and love. He's ugly— physically undesirable—and yet married to Aphrodite, the goddess of love, beauty, and procreation. In the first excerpt above, Aphrodite is the "goddess" who's referred to. But insofar as Hephaestus is a stand-in for the name Hulga, Hulga herself is the goddess being summoned. So in her "highest creative act," she is beautiful.