Gemstone Mine

Gemstone Mine Slot Review

Slot Provider: Stakelogic

RTP: 96.11% | Variance: Medium-High | Maximum Win: 7,500x

Our Score: 7.8

Play at Grand Ivy Casino

WHY YOU CAN TRUST THIS REVIEW: The information and opinions on this page are the result of an comprehensive process of information gathering and live game testing by the gambling experts who work at Find out more here.

About Gemstone Mine

Reviewed by:

Published Date: 17th May 2024

How We Review Slot Games

We test and rate all slot games across 5 criteria, assigning a score out of 10 for each and an overall score that is an average of the 5. To build an accurate assessment of each game we gather information from the supplier and play in real play or demo mode. Find out more.

Gemstone Mine is a cluster pays slot with cascading wins. It is built by Stakelogic and played on an 8×8 grid. Landing clusters in positions adjacent to stone blocks around the edge of the grid reveals multipliers of up to 500x that are applied to the total win from the current spin. The free spins round comes with up to 30 free plays where all multipliers revealed are added to a global total to be applied to the win at the end of the round. Max payout is 7,500x and spins start at 20p.

Gemstone Mine Game Information

  • RTP: 96.11% | 94% | 92%
  • Variance: Medium-High
  • Maximum Win: 7,500x
  • Progressive Jackpot: No
  • Reels: 8
  • Rows: 8
  • Paylines: Cluster Pays
  • Minimum Stake: £0.20
  • Theme: Mining
  • Features: Cascading Wins, Multipliers, Free Spins

Testing Notes: Here’s What Happened When We Played Gemstone Mine

IMPORTANT: To give you an accurate assessment of the games we review our writers play 200 spins. Whilst this is a useful tool to help us review games and to give an example of what might happen when you play, keep in mind that 200 spins is only a very small sample and cannot be used to accurately predict what might happen over another 200 spins. The outcome of all slots play is always random.

Boom Or Bust? Our Session By The Numbers

I played 250 spins on Gemstone Mine on Stakelogic’s test server prior to release to test the game. This is what happened.

  • Stake Size: 1
  • Start balance: 5,000
  • End balance: 4,830.5
  • Hit Rate: 26.4% (66 winning spins in 200)
  • Biggest Win: 6.6x
  • Free Spins Round: 0

The combinations of cascades and multipliers in Gemstone Mine look very promising but sadly this short session didn’t reveal much in the way of thrills. The win rate wasn’t bad at 26.4%, but it felt like the game never really got out of first gear. Far too many near misses where a multiplier was partially revealed only for the cascades to end and the game to re-set before it could get interesting. I did get to a 9x multiplier at one stage but the total win from that spin was only 5.4x! And as for the free spins round … never even got close.

A 6x multiplier in Gemstone Mine
An underwhelming 6.6x win from a 6x multiplier!

Gemstone Mine might have a lot more to offer on another day, but this time round it just wasn’t ready to pay. Perhaps it is more volatile than its’ medium-high rating suggests.

What We Liked

  • Huge multipliers of up to 500x
  • Multipliers accumulate in free spins round for huge final payout
  • Awesome production with great visuals and sounds
  • Get up to 30 free spins!

What We Didn't like

  • Lower RTP at some slot sites

Gemstone Mine Review Scores

  • Theme and Design 9
  • RTP and Variance 7
  • Maximum Win 7
  • Symbols and Paytable 8
  • Features and Gameplay 8

What Our Reviewer Says ...

"There is a potent mix of multipliers, cascades and free spins in this game, but it is very hard to unlock!"

Overall Score: 7.8

Theme & Design

Our Score 9

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.

Gemstone Mine by Stakelogic
Gemstone Mine – awesome production

RTP and Variance

Our Score 7

What is RTP?

RTP (Return to Player) refers to the amount a game will pay out in cash prizes expressed as a percentage of all the money wagered on that game. For example, a 96% RTP means a game will pay out £96 for every £100 wagered. This is an average number and will vary from one session to the next.  Read more here.

What is Variance?

Variance refers to how far a game will deviate from its RTP over time. High variance games deviate a lot and produce uneven win distributions and unexpected windfalls. Low variance games provide a more stable and even distribution of wins. Read more here.

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

Our Score 7

What Is Maximum Win?

Maximum win refers to the maximum amount a player can win from one spin. It is expressed as a multiple of the stake. For example, where the maximum win is 100,000x, from a £1 stake, the maximum win would be £100,000.  

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

Our Score 8

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.

Gemstone Mine Paytable
The paytable with 300x for 15 or more top paying gems

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

Our Score 8

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.

Useful Tips When Playing Gemstone Mine

Remember, online slots are games of chance, there is NO strategy that can improve your odds of winning. However, reading our review and following these tips will help you get the most out of your time playing this slot game.

1. Keep Your Eyes On The Stone Blocks Around The Grid

The multiplier feature in Gemstone Mine is a powerful one so keep your eyes on those stone blocks and hope they reveal some big numbers in base game AND free spins round.

2. Look Out For Dynamite Sticks Too

Those dynamites will earn you free spins AND extend the round when they land during the feature itself. So watch for them. Free Spins is where the biggest wins will come thanks to that cumulative multiplier.

3. Choose A Sensible Stake

Remember, this is a volatile slot so it can burn your balance fast. Use bankroll management and set your stake to a low value so you don’t run through your cash too quick whilst chasing those wins.

4. Play At Our Recommended Slot Sites

We have chosen the sites on this page because they score highly in our reviews and they are licensed by the UK Gambling Commission. That makes them fair and safe places to play slots.

Who Made Gemstone Mine?

  • Name: Stakelogic
  • Established: 2015
  • UK License: Remote 055512-R-331689-004
  • Total Games: 160 +
  • Known For: Branded slots, Megaways games, innovative features, super stake
  • Popular Slots: Rambo, The Expendables, Fruit Storm, Dracula, Jaguar Strike
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