I wanted to bring some attention to the current state of Growing/Polishing alchemy stones and to their prices on the Central Market.
There's quite a few issues in process of making one as well as absolutely outdated maximum prices on Central Market.
Let's start with prices, since it's much easier to update.
1) Polished/Sturdy Alchemy Stones are pretty good on CM but slight increase in price, with a maximum price in 700mil to 1bil should be fine.
2) Sharp Alchemy Stones are on preorders at the current price of 1.1 bil, it's much cheaper to buy it for one single try than making one, price is outdated, should be raised.
3) Resplendent Alchemy Stone, a lot of preorders, they do not downgrade on click, impossible to buy unless Shakatu Event is going on. Price in 5 billion silver is not even close to the price of making one yourself, not even including the time investment.
4) Splendid, CM price is 13billion silver in 2024 with the average price of making one is around 400bil silver and 100+ hours of non stop Growing/Polishing is just a joke. Price should be updated.

Summary on current state of prices:
Sturdy/Polished - fine, requires small adjustment.
Sharp/Resplendent - price should be updated since price of making one is much higher.
Splendid - maximum price should be increased up to 300-500 billion silver.

Of course in order to balance price of Splendid we should adjust some RNG boxes as well.
Example: Shakatu Secret Box which can give you Splendid Alchemy Stone and if it's sellable in CM for 500bil, we kind of have to replace it with Resplendent.

Now to the issues of Growing/Polishing stones:
1) Time, even when you have required resources to make Splendid you have to spend up to 100-150 hours to just polish and grow. I never seen anyone to enjoy or be excited to make so many grow attempts and that's, I think, a biggest blocker for many people and the reason they give up on making better stone, it's boring, time consuming and it feel pretty pointless when you trying to get that Sturdy 1 in 30 attempts for another 3-4% chance to get to the Sharp.
2) Probability of success, we had to analyze and work with a lot of data and statistics to see the chances of success, downgrade and destruction of the stone. I think we did a good job here, maybe it's time to reveal those chances so we're stop walking in shadows and we can play with a system and look for more optimal ways to Grow Alchemy Stones.
3) Different materials give different amounts of XP during polishing process, we might do some small adjustments here since the prices and material availability shifted during last years but the Alchemy Stone Upgrade System wasn't touched at all (Except those 2 skip buttons)

Summary/Suggestions on Growing/Polishing stones:
Multiply the success chance to make Sturdy/Sharp alchemy stones as well as multiply the resources required to polish them so price of making one will stay the same but the time it takes will be reduced and it will be possible to make in a reasonable time frame.
For example: 15-20% chance of success, but 800 ingots to get to 100% polish.
It should be done at least for making Sturdy Alchemy Stones since Polished -> Sturdy is the biggest time sink in the whole process.
Ideally it should be done for Sharp stones as well, but for the Sharp i think doubling the chances & resources should be enough.
That's all I wanted to suggest, stones look pretty good for endgame builds but we have a lot of issues with the system at the moment, I'd be happy to see Alchemy stones market alive again.
A lot of Content Creators struggle to get them, there's no way to get them for average players and we're talking about Splendid, there's Shining that I haven't seen yet.
Also it feels unfair because they were available many years ago and some people got them pretty easily and now it feels impossible.

P.S. It's just a suggestion, I'd be happy to see any other approach that will reduce time of making the stone, I just brought the simpliest solutions and those that could be implemented in hours worth of Developers time.

Allow us to use Crons to protect downgrade/evaporation of alchemy stones.  For me that would be enough.  I can slam materials into something all day, I doubt I will ever sell a Spendid or Resplendant after I made it anyways, so the sale price is a non factor.

With a increased prices lifeskillers might start looking for potential profit for them, there's a chance to make a double upgrade on stones that could play a major role for them during growing etc. Just to make the system alive again and the market around will make a great influence on everything and sure thing you won't sell your first splendid, but what if you prepare like 30 resplndent stones and after all you got 2 of them. You will have a choice to sell it for 500 bil or click it with 3% chance for Shining. Right now 12 bil is nothing so you would click it, would you do the same if you could get 500 bil out of it?
Crons will do just fine, it's that, how much Crons you will have to spend for a single click. Crons on Resplendent to Splendid should be like 15k or something, on Splendid what, 100k?

I think a good change would be to simply make a change where sturdy cannot downgrade anymore. 

CM price adjustments would be good too.

That would be a good first step.

Edit:  maybe also add functionality similar to that combo bag they just added, where you could polish more than one stone at a time automatically - instead of the doing the 11 physical motions required to polish one stone multiplied by the number of stones you want to polish before clicking to upgrade

No downgrade for sturdy will simplify it a lot, but it will also decrease price a LOT, the main goal is to preserve the price of making it but to reduce time and pointless clicks.
The button to "Polish all" would be great but we have to be able set how much polish % we want, other than that I'll take that as a solution.

The huge Problem is that there has not been a single QOL to this and therefore the wasted time is the Killer here. Its a bad desing from UX perspective since the user has to click the same 3 buttons for countless hours. 

A "Polish-all (selected grade and lower)" Button and "Auto grow (selected grade and lower)"  would be a good start to reduce the Time wasted