Theme & Design

Nicely Produced Gem Slot With Atmospheric Underground Setting

Gemstone Mine is a beautifully crafted slot with superb visual production. It is set in a dark underground stone cavern, with firepits, glowing gemstones and axes flanking an 8×8 grid with glowing stone blocks around the edges. What place and time setting we are in is unclear but the style is kind of fantastical and cinematic, a sense that is enhanced by the rising orchestral soundtrack. It’s an interesting take on the gem slot theme and worth loading up just to take in the unique style Stakelogic bring to the table.

RTP and Variance

There are three RTP settings for Gemstone Mine – 96.11%, 94% or 92%. The optimum RTP of 96.11% is good for an online slot but be careful because many UK slot sites will run the game at 94% or 92% which you want to avoid. You can check what rate the game is set to by hitting the hamburger button in the bottom left of the screen then the ‘?’ icon. This brings up an info screen which shows Theoretical Payback Percentage or RTP.

In our own testing we have found that popular casinos that run games at high RTP levels are Casumo and Barz Casino (White Hat Gaming).

Stakelogic reckon Gemstone Mine has a medium-high variance so it will be a volatile slot with good win potential, but uneven distribution. It can burn your balance fast so choose a suitable stake.

Maximum Win

The top win in this slot is 7,500x, which is a little disappointing for a volatile cluster pays game like this one. If you want to play for bigger potential then I recommend reading our article on slots with the highest max wins.

Symbols and Paytable

So the game grid is an 8×8 one and you’ll need to form clusters of 5 or more identical symbols in horizontally or vertically adjacent positions to trigger wins. Clusters can grow in size to become huge. Payouts max out at 15 or more symbols in one cluster.

You’ve got 7 colored gems in the paytable – orange, purple, blue, yellow, red, lighter purple and cyan. Their values go from just 0.2x for 5 oranges up to 300x for 15 or more cyans.

There are no wilds in the game.

Features and Gameplay

Cascading Wins

Like many cluster pays slots, Gemstone Mine is a cascading wins game. That means after each winning spin, winning symbols are removed from the grid, remaining symbols and new ones from above drop down to fill the spaces. If more clusters form then the process repeats until no more wins are triggered.

Multiplier Symbols Up To 500x

Gemstone Mine brings multipliers into play using an interesting mechanic. The multiplier values are displayed behind stone blocks on reels 1 and 8 and rows 1 and 2 at the bottom of the grid).

To unlock the power of the multipliers, a cluster must form adjacent to it. First time round this will partially reveal the multiplier. The second time a cluster forms adjacent to the multiplier, it is completely revealed and its value is applied to the total win for that spin.

If more than one multiplier is revealed during a spin and subsequent cascades then their values are added together before being applied to the win.

But your multipliers don’t last – they are covered over again once the spin is completed.

And finally, you’ll notice that once a multiplier is revealed its value is stored to the left of the grid, meaning the space it vacated is now free for pay symbols to land on in subsequent tumbles. Effectively, the grid is growing in size!

Free Spins Bonus Round

Look out for the bonus symbols represented by the dynamite sticks. These are like scatters – they trigger the free spins round as follows:

• 4 Bonus Symbols – 10 free spins
• 5 Bonus Symbols – 15 free spins
• 6 Bonus Symbols – 30 free spins

NOTE: You can extend the round by a further 5 spins by landing 3 more scatters at any time during a free spin and subsequent cascades.

Now the game changes in your favour. Because during the round ALL multipliers are added to a global win multiplier which will be applied to your total free spins win at the end of the feature. That gives you potential to build a big, big multiplier!

And … after multipliers are revealed on the outer reels and bottom rows these positions do NOT re-set between spins, so your grid just keeps growing, giving you more chances to create bigger clusters.

Super Stake

With Super Stake you can add 0.25x to each bet you make to increase the odds of triggering the free spins round by adding more bonus symbols to the reels.

The Final Verdict

Gemstone Mine has all the makings of a great slot thanks to excellent production and a powerful mix of multipliers, cascades and free spins. However, it comes with a word of warning. As I found out in my short test session … it can be a grind too. You may be waiting a long time for that big sequence to drop. And you may be teased many times with half-revealed multipliers. I’m sure there are big moments to be had, but it might just take a lot of patience, and betting, to get there.