Fastest way to get aquamarine?

[stoneinfocus]

I know you can start getting aquamarine at level 40 of the mines, but I only need one and I was just wondering if there's a certain level it always or almost always spawns so I don't have to go through so many levels.

[Nakos]

As far as I know, it's random (level 40 and below).

Look for the gray nodes with blue stones: http://stardewvalleywiki.com/Mining#Nodes

[Mrrshan68]

You can also randomly find them in fishing treasures too.
Sadly there isnt any specific place where you will see an aquamarine node. Best bet is to go to lvl 40 with some + luck buff from food.

[timewar]

"fastest" = buy omni geodes in desert and open them.

[Pristine1281]

They do appear in crates in the 'ice lvls' of the mine too. Those areas are your best bet. Also, it does help when you reach a certain lvl for your Mining skills. Pick the geologist route and more gems will appear. Than when you reach lvl 10 in mining skills, you can pick Excavotor to find more geodes, which produce gems. I did that I get A LOT of gems this way, and it helped my chances of getting a Prismatic shard, which is the rarest gem in the game. Keep at it and you'll find an aquamarine.

On a side note, you'll have the chance to create a machine that makes gems too, but you have to have one of each at least.