State of repaired object by Reparo spell [Repairing Charm]

Question

Say I have a statue in my garden. It's very old and thus has moss growing on it and certain scratches and chips/pieces missing from over the years.

But now someone ran into it and it fell, completely destroying the statue in tens of pieces.

I'm about to cast "Reparo", how will my statue be repaired?

How does Reparo know 'how' to repair the statue? Will it repair to its previous 'state'? The state where I like it, with the moss, scratchy look. Or will it repair to the brand-new 'original' state? With pearly white marble no moss and without any scratches?

Is this ever addressed in the books or something of the sorts? Is it open to interpretation, where you have to 'concentrate' on how (much) you want something repaired?

Answer 1

In Chapter 4 of Harry Potter and the Half Blood Prince, Dumbledore and Slughorn use Reparo to fix Slughorn's Resident.

They stood back to back, the tall thin wizard and the short round one, and waved their wands in one identical sweeping motion. The furniture flew back to its original places; ornaments reformed in midair, feathers zoomed into their cushions; torn books repaired themselves as they landed upon their shelves; oil lanterns soared onto side tables and reignited; a vast collection of splintered silver picture frames flew glittering across the room and alighted, whole and untarnished, upon a desk; rips, cracks, and holes healed everywhere, and the walls wiped themselves clean.

As we can see, part of the spell is also cleaning.

However, there is also an instance when the spell didn't clean. In Harry Potter and the Half Blood Prince chapter 11, Harry switches the covers of 2 potion books- One of them is stained and old-looking, and the other is brand new.

He pulled the old copy of Advanced Potion-Making out of his bag and tapped the cover with his wand, muttering, “Diffindo!” The cover fell off. He did the same thing with the brand-new book (Hermione looked scandalized). He then swapped the covers, tapped each, and said, “Reparo!” There sat the Prince’s copy, disguised as a new book, and there sat the fresh copy from Flourish and Blotts, looking thoroughly secondhand.

We can determine from this that in some instances the spell would clean, and in some it won't. It probably depends on the intention: Harry intended to disguise the Prince's book as a new one, but didn't really care how the new book's cover looks, so the spell didn't clean the cover. On the other hand, Dumbledore and Slughorn intended for the house to look brand new, and that's why the spell also cleaned the house for them.

Answer 2

Probably Just Put the Pieces Back Together

While we don't, to my knowledge, have anything definitive on the matter, it would likely just put the recently-broken pieces back together and not fix all the chips/scratches/whatever it's had over the years. That seems to be what we get from the various uses of Repairo in the books (fixing Harry's broken glasses for instance). They're always described as being "fixed" but never described as being "brand new" or looking "new" which by pragmatic implication means whatever minor defects they had prior to being broken weren't fixed.

However we ALSO know that Repairo operates differently at different levels of power. Take Harry's Wand in Harry Potter and the Deathly Hallows for example. It's broken almost completely in two, and the initial attempt to mend it sticks the two halves back together, only for it to fall apart the instant Harry tries to use it. Meanwhile at the end of the book when Harry uses the (ostensibly more powerful) Elder Want to repair his own wand, it works perfectly. So theoretically a more powerful version of the Repairo spell might be capable of putting your 10 pieces back together and fixing all the chips and scratches.

Answer 3

The magical effect of a spell is as much up to the skill and intention of the caster as it is the incantation.

We see this most often with partially transfigured objects when Hogwarts students are first learning spells.

In the case of Reparo, as @MBEllis mentioned, we see both repair to previous condition and improvement. It makes the most sense for this to vary between casts and casters.