Could George's ear have been healed by Snape?

Question

In Harry Potter and the Deathly Hallows George's ear gets cut off by a stray Sectumsempra (cast by Snape).

Now this was an act of Dark Magic and therefore George's ears could not be healed:

Mrs. Weasley looked around and said, “I can’t make it grow back, not when it’s been removed by Dark Magic. But it could have been so much worse. . . . He’s alive.”

- Molly Weasley - Fallen Warrior (Harry Potter and the Deathly Hallows).

But in Half-Blood Prince Snape clearly heals Draco Malfoy's wounds (inflicted by Harry's Sectumsempra), using some incantation and tracing his wand over the wounds:

The door banged open behind Harry and he looked up, terrified: Snape had burst into the room, his face livid. Pushing Harry roughly aside, he knelt over Malfoy, drew his wand, and traced it over the deep wounds Harry’s curse had made, muttering an incantation that sounded almost like song. The flow of blood seemed to ease; Snape wiped the residue from Malfoy’s face and repeated his spell. Now the wounds seemed to be knitting.

- Sectumsempra (Harry Potter and the Half-Blood Prince).

If Snape was available, could he have healed George's ear?

Whilst writing this question, I have realised that George's ear was cut off, and not just injured. This may make a difference; perhaps George's ear couldn't have been re-grown due to being severed using Dark Magic.

Answer 1

I don't think you wanna read too much into Snape's treatment of Malfoy's wounds.

First of all, Harry has never used the spell before and used it in a state of panic. He 'wav[ed] his wand wildly' and did not get a clean hit.

[W]ater poured everywhere and Harry slipped over as Malfoy, his face contorted, cried, 'Cruci-'

'SECTUMSEMPRA!' bellowed Harry from the floor, waving his wand wildly.

Harry Potter and the Half-Blood Prince - p.489 - Bloomsbury - Chapter 24, Sectumsempra

What's more, he seems to have cast the spell with minimal malice and intent:

'You know I wouldn't've used a spell like that, not even on Malfoy, [...]'

Harry Potter and the Half-Blood Prince - p.495 - Bloomsbury - Chapter 24, Sectumsempra

So these are flesh wounds, really, cuts. Cuts caused by Dark Magic, yes, but as you raise in the question, nothing has been cut off.

Even so, there is still some risk of scarring, even though a powerful wizard and the creator of the curse, attended the scene immediately. Although circumstantial evidence suggests Malfoy escaped scarring:

'You need the hospital wing. There may be a certain amount of scarring, but if you take dittany immediately we might avoid even that ... come ...'

Harry Potter and the Half-Blood Prince - p.489 - Bloomsbury - Chapter 24, Sectumsempra

So my first point is obviously that this was an inexperienced casting of an advanced spell, and it wasn't a clean hit.

But I think more important is the point you raise in the question and that I have already touched on.

Molly (and, through her, the author) is quite explicit in Deathly Hallows:

'I think so, although there's no chance of replacing his ear, not when it's been cursed off -'

Harry Potter and the Deathly Hallows - p.64 - Bloomsbury - Chapter 5, Fallen Warrior

Body parts removed by Dark Magic cannot be put back on.

Whereas in the case of cuts, scratches, lacerations and so on things are a little different. Look at Bill. He was savaged by Fenrir Greyback, but nothing was bitten off. He was scarred, but even there his wounds were closed.

'No, I don't think that Bill will be a true werewolf,' said Lupin, 'but that does not mean that there won't be some contamination. Those are cursed wounds. They are unlikely ever to heal fully, and - and Bill might have some wolfish characteristics from now on.'

Harry Potter and the Half-Blood Prince - p.572 - Bloomsbury - Chapter 29, The Phoenix Lament

He can't be healed fully, but it was possible to improve upon

an unrecognisable face lying on Bill's pillow, so badly slashed and ripped that he looked grotesque.

Harry Potter and the Half-Blood Prince - p.572 - Bloomsbury - Chapter 29, The Phoenix Lament

To the point where, bathing in Fleur's radiance at the wedding,

Bill did not look as though he had ever met Fenrir Greyback.

Harry Potter and the Deathly Hallows - p.121 - Bloomsbury - Chapter 8, The Wedding

Although this is only 'once Fleur had reached him' and he is described as "badly scarred" before the battle of the seven Potters.

Having said that, it is noticeable that the wounds caused by Harry's Sectumsempra are much more easily healed, so we might posit that Sectumsempra is much weaker than the curse imparted by Greyback and if it was possible to heal Malfoy's wounds it was possible to heal George's.

Madam Pomfrey was dabbing at his wounds with some harsh-smelling green ointment. Harry remembered how Snape had mended Malfoy's Sectumsempra wounds so easily with his wand.

'Can't you fix them with a charm or something?' he asked the matron.

'No charm will work on these,' said Madam Pomfrey. 'I've tried everything I know, but there is no cure for werewolf bites.'

Harry Potter and the Half-Blood Prince - p.572 - Bloomsbury - Chapter 29, The Phoenix Lament

But I would argue that even in Malfoy's case, he was at risk of scarring from Harry's inept slashing. So I don't personally think Snape's ability to heal Malfoy's cuts implies that ears, once cursed off, could be reattached, not given Molly Weasley's direct statement and the state of Mad-Eye Moody after years as an Auror.

Or to state my point more plainly. I would argue that, if Bill's wounds can be treated to the point where he is scarred, but the wounds are healed, which is to say they are closed and he is no longer bleeding, then it should come as little surprise that Malfoy's injuries caused by Harry's clumsy use of a spell he did not understand could be almost completely cured leaving little or no trace. But that does not imply that if the same curse is used by an experienced caster to remove a body part, that that body part can be reattached by magic. You provide in your question a flat statement to the contrary, and my intention with the answer is to show why I don't think there are sufficient grounds to object to it.

Answer 2

From the sectumsempra wiki

Though the aforementioned healing spell may heal the wounds and dittany may prevent scars, any body parts that have been severed by this curse cannot be grown back (a trait of dark magic's permanent effects), as demonstrated by George Weasley when he lost his left ear to the spell.

So no, Snape couldn't have healed George's ear

Answer 3

Speculation: it could have, but only by Snape.

Snape uses the Vulnera Sanentur spell to heal Malfoy's wounds when Harry attacks him using the Sectumsempra spell, so I suppose the spell had that only antidote.

Some may argue that cursed wounds can't be healed, but it could be more like snake venom: any antivenom couldn't be used against any venom, but pairing the correct antivenom with the venom does work. Can't know for sure, since Snape isn't there to actually cast the spell.