Was it Tom Riddle's diary that Ginny left at The Burrow?

Question

I was just reading the Chamber of Secrets again and I noticed something. While leaving the Burrow to get to King's Cross, the Weasleys had to turn around three times because George, Fred and Ginny had forgotten items they wanted to bring to school.

They had almost reached the highway when Ginny shrieked that she'd left her diary. By the time she had clambered back into the car they were running very late and tempers were running high.
_{Harry Potter and the Chamber of Secrets, Chapter: The Whomping Willow, Page 66}

Was that her diary that she had had for years? Or was it the new one obtained from Lucius Malfoy? Did Ginny even have a diary prior to Tom's? Does anyone know if JKR has ever commented on this?

The entire second book would have been different if they didn't allow Ginny to go back for the diary. Of course she probably would have asked her mother to send it by owl, so maybe it would have been exactly the same.

Answer 1

It's very likely to be Riddle's diary.

Ginny herself says that she came across Riddle's diary when unpacking the books which they'd bought in Flourish and Blotts.

"Why didn't you show the diary to me, or your mother? A suspicious object like that, it was clearly full of Dark Magic!"
"I d-didn't know," sobbed Ginny. "I found it inside one of the books Mum got me. I th-thought someone had just left it in there and forgotten about it..."
_{(Chamber of Secrets, Chapter 18, Dobby's Reward).}

It's not clear how much time passes between this shopping trip and the Weasleys leaving the Burrow for the start of term. Nevertheless, it wouldn't have taken long for Ginny to unpack her bags, come across the diary and see it as "her diary". As soon as she found it she seemingly assumed that it had been left for her and consequently took possession of it.

Even without this titbit from the text, logic would suggest that she didn't have another diary. If she had one already that she was using then she would have no need for another one. The new diary would be discarded and she would continue using the one she already had. This didn't happen, which suggests that she only ever had one diary - the Riddle diary.

Out-of-universe, as Raditz_35 points out, referencing the diary - which would eventually become a critical part of the whole book's plot - early on in passing seems like a characteristically Rowling-esque thing to do. Rowling is well known for slipping in seemingly innocuous items into mundane paragraphs which later become crucial to the story. Examples include the locket horcrux in the Black house, the diadem horcrux in the Room of Hidden Things and Neville's book on Magical Herbs and Fungi. It wouldn't be at all surprising if this was a playful hint hidden amongst a deluge of detail on Rowling's part. As the question points out, it raises an interesting 'what if' scenario which I suspect may have amused Rowling even if she didn't expect her readers to spot it.

Answer 2

To the best of my recollection, she did not have two diaries in Chamber of Secrets (or in any of the books, explicitly mentioned).

Thus, we must conclude that it was Riddle's diary (read:

Horcrux

) that she had left behind and was unwilling to depart without. There's no explanation for why she didn't just ask her parents to send it along afterwards as an owl delivery.

Answer 3

It almost certainly was Riddle’s diary that she’d left at the Burrow.

Though it’s not mentioned whether Ginny typically kept a diary before or since being given Tom’s, it’s very likely the diary she wanted to go back for was that one. It’s unlikely that the mention of Ginny being upset at leaving a diary behind was coincidence, when her having that specific diary becomes very important later on. Also, she was very attached to Tom’s diary when she had it, she considered him like a friend, so it’s likely she’d be very unwilling to leave it behind, even for a bit.

“It’s very boring, having to listen to the silly little troubles of an eleven-year-old girl,’ he went on. ‘But I was patient. I wrote back, I was sympathetic, I was kind. Ginny simply loved me. No one’s ever understood me like you, Tom … I’m so glad I’ve got this diary to confide in … It’s like having a friend I can carry round in my pocket …”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 17 (The Heir of Slytherin)}}

It being Tom’s diary would explain why she was unwilling to part with it even for a short amount of time, and just have her parents owl it to her at Hogwarts rather than make them late - she was very attached to it, and additionally, it had a way of making people unnaturally interested in it from first contact. Harry found it soaking wet in toilet water, and knew from looking at it that it was blank.

“Harry peeled the wet pages apart. They were completely blank. There wasn’t the faintest trace of writing on any of them, not even ‘Auntie Mabel’s birthday’, or ‘dentist, half past three’.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 13 (The Very Secret Diary)}}

Despite it being blank and soaked in toilet water, Harry takes it with him, for no logical reason.

“Well, it’s not much use to you,’ said Ron. He dropped his voice. ‘Fifty points if you can get it through Myrtle’s nose.’

Harry, however, pocketed it.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 13 (The Very Secret Diary)}}

After that, Harry still kept picking the diary up to read it despite already knowing it was blank.

“Harry couldn’t explain, even to himself, why he didn’t just throw Riddle’s diary away. The fact was that even though he knew the diary was blank, he kept absent-mindedly picking it up and turning the pages, as though it was a story he wanted to finish.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 13 (The Very Secret Diary)}}

Harry had no clear reason to be carrying this diary and yet he did until Ginny panicked and stole it back. Ginny had far more reason to feel connected with it, since she considered it her diary with a friend inside it, so she’d be likely even more reluctant to part with it for any reason.