Is there lore that reveals where the first seed from the Wizard of Wines winery went?

Question

In Curse of Strahd,

there is a place called the Wizard of Wines that had three magical gemstones (called "seeds") which gave the winery's grapes the ability to grow. According to the campaign book (pg. 173), the second seed was taken by Baba Lysaga (who still possesses it) and the third seed was taken by evil druids and implanted in the tree blight Wintersplinter to power it.

I can't find any indication of what happened to the first seed beyond this info:

Ten years ago, one of the vineyard's magic gems was dug up and stolen, and as a result, the winery stopped producing its best vintage, the champagne. No one knows what happened to the gem.

Is there any indication from another source of what happened to the seed? Or is it just an open quest hook for DMs?

Answer 1

There is no official lore

You can see from this tweet exchange by Chris Perkins, the Lead Designer for CoS:

Ben Latham @SassyWyvern
@ChrisPerkinsDnD Where is the third magic gem that was at the Winery in CoS? Can't find it anywhere in the book. Am I just blind

Christopher Perkins @ChrisPerkinsDnD
You're not blind. Its whereabouts is not revealed in #CurseofStrahd (deliberately).

As there is intentionally no information on the where the third seed is or what happened to it, it is up to the DM to decide what happened to the third seed, as he confirms in this followup tweet:

Josh Watson @josh_watson
@ChrisPerkinsDnD Is it deliberate in that you want us DMs to invent an explanation, or because it might show up in a later publication

Christopher Perkins @ChrisPerkinsDnD
DMs should feel free to make the search for the lost gem part of their campaigns.

Answer 2

Only two of the gems' locations are in the adventure

The opening of chapter 12 (p. 173) describes that each gem was taken.

Ten years ago, one of the vineyard's gems was dug up and stolen ... No one knows what happened to the gem.

... the wereravens have been fending off attacks by Baba Lysaga's scarecrow constructs. Three weeks ago, during one such attack, another gem was found, dug up, and taken. Davian believes that it is in the possession of Baba Lysaga ... Davian's belief is correct ...

Five days ago, evil druids stole the third and final gem and bore it to Yester Hill ...

So, we know that the second is with Baba Lysaga (confirmed on p. 163 and p. 166 when describing her hut) and that the most recent was taken to Yester Hill.

On p. 198, it reveals the location of the most recently stolen gem:

Planted in the "heart" of this wooden effigy is a magic gem stolen from the Wizard of Wines vineyard

There's also a special event (on p. 200) called "Druid's Ritual" that describes the druids awakening this wooden statue to summon a tree blight to attack the winery. Also on p. 180, the special event "Wintersplinter Attacks", which is this same tree blight attacking the winery.

How I resolved it

The gem in Wintersplinter and the gem in the wooden statue is the same gem, but in my game I had it be two separate gems. Since I ran the latter special event, the party did not witness Wintersplinter's creation, so the gem used to power that tree blight was the latest lost gem, but when they went to Yester Hill after that, I had the statue be still intact, containing the 10 years ago gem. Wintersplinter was just an awakened tree in my run of this, rather than being related to that statue.

For all three gems to be part of the adventure, you would need to improvise and adjust some details like I did, or otherwise add it to the world yourself. It's up to the DM.