Can a 9th LvL School of Conjuration Wizard use its Minor Conjuration, create an Inanimate object ability, to create a jewel worth 1,000 gp to cast Planar Binding? 

 No. Planar Binding takes an hour to cast, and the object created by Minor Conjuration lasts for an hour, so it would disappear 6 seconds (ie one action) before the hour elapses.

And on top of what Pocketmouse said, Minor Conjuration doesn't say that the clearly magical conjured item has any value, unlike Creation Bard, so it wouldn't be able to be used for spell components with a cost. Sure, you're in a place and got no spells, so you conjure bat guano to cast Fireball, that'd be okay, but not a gem.

(that MAY be my own DM ruling without a solid firm grasp in RAW, but I can't see any other way to read it)

I think the argument DevanAvalon presents depends entirely on interpretation of what the component's value represents for a specific spell: its market price or a shorthand for its physical properties.

Consider the 50gp diamond required for Chromatic Orb. If a merchant has a suitable diamond for sale and I haggle them down to 45gp does that affect the ability to cast the spell with this diamond? IMO the answer to that is no because in this case I interpret the gold piece value of the required diamond to be a shorthand for a diamond with specific size, cut, colour and clarity minima. Under this interpretation Minor Conjuration should be able to replicate a diamond with those properties despite having no market value.

In contrast, Revivify requires diamonds worth 300gp, which are consumed. It could be interpreted that this is a magical trade, in which case the market value of the diamond(s) is what matters not its properties, in which case Minor Conjuration should not be able to create a suitable spell component.

This approach obviously requires a (potentially ongoing) conversation between the player and DM as to what is and isn't acceptable.

Swamp_Slug is correct.  The PHB never clarifies what "worth" means.  Even the popular interpretation of it as "cost to buy" is no more or less RAW than "cost to make" (see e.g. Booming Blade for a spell with a craftable M component).  Do spells depend on local market values?  No-one knows, even though it's impossible to engage in Curse of Strahd without having an answer.

It's clear from the developers intent that market value isn't a thing. If you need a 50g diamond for a spell component - you buy one for 50g. Done.
I hate quoting tweets from JC because I find his rulings make sense less than half the time - but still - I'm quoting intent here.

JC Tweet
D&D has no official rules for the fluxation of prices in a living economy. The game’s prices are a fixed abstraction. If modeling a realistic economy in the game is your bliss, you’ll need to do it without the safety net of official rules.

So if you create a fluctuating market in your game - you're on your own - basically.

Quote from Emmber >>

It's clear from the developers intent that market value isn't a thing. If you need a 50g diamond for a spell component - you buy one for 50g. Done.
I hate quoting tweets from JC because I find his rulings make sense less than half the time - but still - I'm quoting intent here.

JC Tweet
D&D has no official rules for the fluxation of prices in a living economy. The game’s prices are a fixed abstraction. If modeling a realistic economy in the game is your bliss, you’ll need to do it without the safety net of official rules.

So if you create a fluctuating market in your game - you're on your own - basically.

Have you read the rules for Curse of Strahd?

That's the rules specifically for CoS - not general play.

Besides - I did say his rulings make sense less than half the time.

Quote from Emmber >>

That's the rules specifically for CoS - not general play.

Besides - I did say his rulings make sense less than half the time.

Agreed on both points.  It's all very confusing.

Quote from quindraco >>

Quote from Emmber >>

It's clear from the developers intent that market value isn't a thing. If you need a 50g diamond for a spell component - you buy one for 50g. Done.
I hate quoting tweets from JC because I find his rulings make sense less than half the time - but still - I'm quoting intent here.

JC Tweet
D&D has no official rules for the fluxation of prices in a living economy. The game’s prices are a fixed abstraction. If modeling a realistic economy in the game is your bliss, you’ll need to do it without the safety net of official rules.

So if you create a fluctuating market in your game - you're on your own - basically.

 

Have you read the rules for Curse of Strahd?

 CoS doesn't really change the question. It has a different economy than "regular" D&D, but whether the value of components refers to their intrinsic/nominal value or the value they were or could be traded for is equally unclear in either case. 

With regards to the tweet: my interpretation is that you (are supposed to) use the nominal price - if you haggle it down you get your 50 gp diamond for 45, but it still counts as 50 for component purposes; if you get swindled you might get sold a 35 gp diamond for 50, and will get a rude surprise when trying to use it for a spell. As for Ravenloft, the same applies: if you need 20 gp worth of incense it'll cost you 200 in Barovia (if you buy from Bildrath anyway), and a single diamond worth more than 25 gp for the purpose of using it as a spell component can't be bought there (again assuming Bildrath is your source).