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Author Topic: Gem  (Read 13834 times)


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« on: April 14, 2022, 08:52:37 AM »
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The look and performance of this high-performance bowling ball make it nothing less than a Gem. The Roto Grip Gem introduces us to the Defiant LRG core which is the lowest RG asymmetrical core in the current Roto Grip line-up. This core enables the ball to rev up fast and continue strong! Not only is the core in this ball noteworthy but the coverstock is the extremely aggressive MicroTrax Solid Reactive. This powerful combination makes this bowling ball perfect for heavy oil conditions.

Color: Citrine/Ruby/Amethyst
All colors do vary somewhat from the picture shown
Coverstock: MicroTrax Solid Reactive
Core: Defiant LRG (14-16#)
Finish: 2000 Abralon
RG: 2.47 (for 15# ball)
Differential: 0.053 (for 15# ball)
Recommended Lane Condition: Heavy Oil
Hook Potential: High
Length: Middle



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Re: Gem
« Reply #1 on: April 18, 2022, 09:11:07 AM »
The newest addition to the HP4 line in the all new GEM. The GEM features the Defiantâ„¢ LRG Core - (the lowest RG asymmetrical core Roto Grip has ever created.). The LRG Core is wrapped with the most aggressive solid coverstock we make known as MicroTraxâ„¢ Solid Reactive. This lethal combination makes bowling on high volume patterns an easy task. I have been pleasantly surprised with this ball, for how strong the ball is the ball is still able to retain energy through the pins. If you are looking for a strong continuous roll, look no further than the GEM. Go out and get yours today!


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Re: Gem
« Reply #2 on: April 19, 2022, 10:59:14 AM »
The Roto Grip Gem features the extremely low RG Defiant LRG Core wrapped in the MicroTrax Solid Reactive coverstock. The RG at 15lbs is 2.47 with a differential of .053 and an intermediate differential of .016. This ball is all sorts of strong…it is strong in the front, the mid, and still has some left for the backend part of the lane, not to mention the strong shelf appeal of this beauty. This ball is great for bowlers who are speed dominant or low rev players. The low RG core gets this ball rolling as soon as it hits the lane, so oil in the front part of the lane is a must for the Gem. For me the box finish of 2000 grit abralon was too much. I had to get some games on this ball just to tame it down somewhat so I could really use it at my home center. For me this ball is different than all the current SPI brand asymmetric balls. The Gem is much more of a heavy rolling ball with a very smooth backend. It is something that I will use on longer and flatter conditions where I need to keep my angles closed. If you are looking for a ball that handles the oil like no other, look no further than the Roto Grip Gem.


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Re: Gem
« Reply #3 on: April 24, 2022, 02:24:17 PM »
Ball Specs:
Roto Grip Gem
Coverstock: 2000-grit MicroTraxâ„¢ Solid Reactive
Weight Block: Defiantâ„¢ LRG Core (Asymmetrical)
Color: Citrine/Ruby/Amethyst

I was excited to hear about this ball. When I saw it would have the Defiant core in the ball, I was really excited. The Defiant line was one of my favorite lines of all time. When I threw the ball I quickly realize that the Gem was going to be an upgraded version of the original Defiant. Much stronger and forgiving if you pushed the ball out. I plan on doing a little more experimenting with surface but out of box this thing cuts through just about any amount of oil that I have run into. I would recommend this ball to just about anyone of any skill level. Do not let this ball go by the wayside make sure you pick yours up soon!
Will Tefft
Roto Grip Staff Member


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Roto Grip Gem
« Reply #4 on: April 27, 2022, 08:59:46 PM »
Roto Grip Gem Review

Rev Rate: 375
Ball Speed: 15-16 mph
PAP: 5 inches over, 1/2 inch up
Layout: 55x5x65

(I have attached a link to the Gem Ball Review that I did on YouTube. Feel free to check it out!)

The Roto Grip Gem is a tank on the front lines of driving through oily league and tournament conditions. The Defiant LRG core gives it a faster revving asymmetrical look with its 2.47 RG, while the MicroTrax solid reactive coverstock gives it that extra aggressiveness to handle any medium to heavy oil conditions. This ball will have no problems getting uphill. The Gem will “dazzle” for you!


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Gem Review
« Reply #5 on: May 01, 2022, 12:13:59 PM »
Ball Specs:
Roto Grip Gem
Micro Trax Solid Reactive
Asymmetric Defiant LRG Core
Finish grit 2000 Sanded

Bowler Specs:
Right Hand. PAP 5” Over 1/2 up
Rev Rate 300. Tilt 20. Rotation 50.
Speed at release 17

This ball hooks! I am becoming more and more impressed with the Roto Grip Gem as I bowl with it. This ball out hooks everything I have including the Proton Physics. When I drilled my first Gem I left it at box finish and it was super strong and hit hard but I had to put it away quickly because as the lanes broke down it was too strong up front an lacked a bit of hit as I moved inside. I have since drilled another one weaker and polished it. The polish makes it look even better and makes it a more angular piece. This was after trying a 5000 wet sand finish which I really like also. The bit of polish helps me stay with this ball longer on heavy oil and I never loose angle. The Gem polished is still an early revving aggressive ball. I still have to ball down sometimes because this ball is so strong. The ball looks great going down the lane and even though it is multi-color I still can see the roll and motion very well on it.
Strong balls are easy to sell and we have moved a good bit so far and the customer feedback it very good. This ball never seems to skid too far and reads the breakpoint easily due to the strong core and cover enhancements Roto Grip has made. I am very happy to have this ball and have already had some big numbers with it.

The Gem hooks early and doesn’t stop.
The Ball has a great look.
This is a must have if you need a heavy oil ball.

Video Link:

Glenn Wendel
PBA Member
Storm Pro Shop Staff

PBA Member
Storm Staff Member
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Rick K

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Re: Gem
« Reply #6 on: May 09, 2022, 01:40:10 PM »
Gem • Performance Line • HP4
Core •Defiant LRG Core
Coverstock • MicroTrax (Micro Nanoparticle Traction) Solid Reactive Finish • 2000 Grit Abralon
Weight • 15 lbs. RG •2.47 Differential • .053 Int. Diff • .016
Layout • 4 x 5 x 2 1/2
Tester PAP • 5" R, 5/8" D Tester Axis Tilt • 11° Tester Rev Rate • 325
Test Pattern • 42' THS (Typical House Shot) • Modified, Kegel Stone Street

There is truth to the statement, "Sometimes evolution can spark new life into technology." And with the release of the Gem, Roto Grip has sparked a brilliant new dimension into their HP4 line. With the Defiant LRG Core and MicroTrax Solid Cover combination, the Gem delivers a powerful, cutting-edge new look to your ball motion. So let's break it down on a THS!

The heart of the Gem is the Defiant LRG Core. And I loved how this core reacted from the first shot! The Defiant LRG Core rev's smoothly and earlier like you would see in a strong symmetrical core. However, when it makes the turn and stands up, it enters the roll phase with a rolling thunder of power! So if you are a straighter, low rev player like me, this core is ideal for your game! And what I found most appealing about the Defiant LRG was although, being it is a low RG core, it flared (hooked) more than expected. Yet it also delivered an impressively powerful continuation through the pins! So down and in, players will love the Defiant LRG's potential to dispense those frustrating ten pins even without having six degrees of entry angle!

The MicroTrax Solid reactive cover is well-suited for straighter and down and in players. And being the MicroTrax is a strong solid cover, you can count on its teeth to bite into heavy oil! Yet, although it is an aggressive cover, I found the MicroTrax Solid didn't overreact to friction. I saw a smooth transition coming off the pattern on fresh oil playing the nine board. Then as the THS pattern began to break down, I liked how this MicroTrax cover blended the wet/dry conditions that developed. And as a straighter player, I enjoyed moving my target in decisively without worrying if I had enough hand to make the Gem turn off the pattern! The MicroTrax cover gave me the confidence to stand left while still retaining the Gem's intense hitting power.

In closing, I was impressed with this new release from Roto Grip! The Gem performs brilliantly for down and in players and those with a challenged rev rate! And with the Defiant LRG's asymmetrical core and the MicroTrax Solid reactive cover, the Gem will be a powerful tool to add to your arsenal. So have your local pro shop operator drill yours up and tweak the Gem's surface today, then see for yourself why the Gem is the jewel in your arsenal!

Rick Klimowicz
Storm Products Pro Shop Staff
Roll the Ball Pro shop
Penndel, PA


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Re: Gem
« Reply #7 on: May 09, 2022, 02:03:02 PM »

Length: 43'
Volume: 21.5 mLs

Type (THS, Sport Pattern etc): THS


Likes: Far more versatile than I ever would have imagined

Dislikes: none so far.

This thing is Suuuuuuper Rolly

This ball is extremely strong. It’s definitely earlier than the Proton Physix and Reality.  This ball will be great to blend those super clipped house shots. This will also be a great piece on those patterns with a lot of volume in the front and not a lot of taper towards the end of the pattern.  It will help control the breakpoint. 
Lastly I want to say that even though this ball is early and rolly, It still has some pop down lane to help get the corners out!.

Other balls getting a lot of play:
Dark Code-4x6x2
UFO Alert-4.5x5x3.75
Altered Reality-4.25x5.25x2


Casey Mattingly
Storm/RotoGrip Staff
Turbo Regional Staff
Coach's Corner Pro Shop
Alexandria, IN


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Re: Gem
« Reply #8 on: May 11, 2022, 09:30:08 AM »
Roto Grip's new high performance bowling ball the new Gem! This ball features the Micro Trax Solid Reactive Coverstock wrapped around the Defiant LRG Core.


If you are looking for a ball to tackle the heavier oil conditions, look no further, this ball just flat out hooks. It starts picking up a roll very early like most heavy oil balls, but where this ball stands out, the recovery on the back end. Most hook balls for me, use so much energy up front, there isn't much movement on the backend, leaving a lot of corner pins. This ball still has enough energy on the end that it snaps them out.


It also takes surface adjustments very well, as I shined it up just see how it would react, I was not disappointed. With shine, it cleared the heads very well, picked up in the mid-lane very well, and had plenty of backend. What impressed me most while shiny, was when I missed to the dry early, it did not jump off the spot, but rather a smoother reaction to the pocket.


Don't miss out on one of the biggest hooks balls on the market right now in the Roto Grip Gem!


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Re: Gem
« Reply #9 on: May 14, 2022, 03:30:30 PM »
Roto Grip GEM
Cover: MicroTrax Solid
Core: Modified Defiant Core
Factory Finish: 2000=grit
My Finish: 4K FAST
Layout: 55 x 2 x 55
Once I heard that the Defiant core was coming back, I was gitty as a kid going to his first tournament. Schlem and the crew at SPI change the core material a little bit to bring it up to today’s game.  Matching the MicroTrax cover to this updated core has added some smiles back onto my face and more strikes in my game. First thing that POPS out is the awesome color choices. You KNOW when the GEM goes do the lane and it really does turn heads on the lane and off the lane. The GEM replaced for me the Roto Grip UFO with more overall continuous motion and also not as early in the front part of the pattern where the majority of the conditioner is located. The GEM moves so well in the front that the energy it stores is the best I have seen in some time for a solid reactive in overall carry and strength going into the pocket. The GEM works well on all lane panels, including wood.  I cannot wait to use this, Storm Nova, Hyped Pearl and Roto Grip Helios at Nationals in late June.


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Re: Gem
« Reply #10 on: May 18, 2022, 06:57:08 PM »
Ball Specs:
Roto Grip Gem
Coverstock: 2000-grit MicroTraxâ„¢ Solid Reactive
Weight Block: Defiantâ„¢ LRG Core (Asymmetrical)
Color: Citrine/Ruby/Amethyst
The Gem is a very vibrant, very strong, very early rolling ball. This ball reminds us of the Reality and the Proton Physix. This ball will be a monster on a fresh house shot. It seems to recover very well if you push the ball to the right so we really can move our feet left and open up the lanes. This ball is also a gem when it comes to continuous motion, and is very noticeable right off the bat. If you are looking for a first out of the bag asymmetrical ball that is very strong and very continuous look no further.

Kyle, Joel, & Dean Johnson
Roto Grip Pro Shop Staffers


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Re: Gem
« Reply #11 on: May 19, 2022, 09:19:50 PM »
Gem - Ball Specs
Cover Stock: MicroTrax Solid Reactive Cover Stock
Finish: 2000 Grit
Core: Defiant LRG Core
Layout: 50 x 5 x 40
RG: 2.47
Differential: 0.053
Intermediate Diff: .016


The GEM is the latest addition to Roto Grips HP4 line of balls. Roto Grip circled the wagons back to the Defiant series to create the Defiant LRG Core by altering the composite shape of this core which makes it faster revving, stronger, and continuous, wrapped in the most aggressive MicroTrax solid reactive coverstock. Not only does this ball look great but it definitely throws it weight around. I tested the Gem on a 44 feet typical house pattern, I was able to play track area and deep inside with great success. The Gem reads early in the midlane and had a lot of energy on the backend for a continuous motion with great pin carry. This is a great ball for all levels of bowlers. Order one from your local pro shop today! My ball review videos are posted on YouTube channel Stanley Waite.

Stanley Waite
900 Global Staff Member
Dover, DE


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Roto Grip Gem review by Trevor Roberts
« Reply #12 on: May 20, 2022, 01:17:49 PM »
Lane Condition
Length: 40
Volume: Medium
Type (THS, Sport Pattern etc): THS

The Gem is possibly the strongest ball in the Roto Grip line. For me, it was a little bit earlier and covered more boards than the Reality! Typically in the bigger asymmetric balls, you will see the ball burn all its energy in the front part of the lane, and go pretty straight down lane. But not the Gem! This ball retained way more energy than I thought it would, and went through the pins very well even from left of 20. I saw the Gem go down the lane a lot when I was on tour, and now I see why. If you want some additional length and energy, don’t hesitate to add some polish. Both Verity Crawley and Anthony Simonson used their Gems with polish, and they looked even better in my opinion.

YouTube Review

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Bowler Stats
Trevor Roberts
2016 PBA Southern Regional Rookie Of The Year
Storm Products / Turbo 2n1 Grips / Bowlifi Staff Member
Right Handed
Rev Rate: 400
Speed: 16
PAP: 5 1/2 up 13/16

Kevin Duncan

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Re: Gem
« Reply #13 on: June 01, 2022, 07:00:58 PM »
Roto Grip Gem
Layout: 4 x 5 x 3.5 Storm Vector Layout
Rev Rate: 325 rpm
Testing information: 41 foot THS (medium to light volume)
Bowling Center: Fulton Bowling Center
Kegel Machine – Brunswick Anvilane

The Roto Grip Gem utilizes the Defiant LRG Core (the fastest revving, strongest continuing, lowest RG asymmetrical core ever offered in the Roto Grip history) and the MicroTrax reactive cover.  The drill layout on the Gem put the pin next two my ring finger and slightly down.  Our intent with the drill was to produce a roll off the end of the pattern (not a jump left reaction) to be used on fresh lane conditions.  We want to be able to keep our target in front of us when needed.  Therefore, the Gem we drilled will not be used to hook the entire lane.  We were impressed with Gem.  The ball reaction was definitely smooth.  The best look we had was further right.  When we missed right, it did not jump left.  We drilled a Gem for a left-hander and he reported that the sound of the Gem hitting the pins was louder than any ball he had heard in his local bowling center.  The Gem’s best characteristic is its forgiveness.  We say the Gem correct a lot of our misses – both in and out misses. #Stormnation


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Re: Gem
« Reply #14 on: June 12, 2022, 06:07:45 PM »
Roto Grip GEM Ball Review

Hey everyone, I’m back with another ball review, and this time it’s for the GEM and in 15 pounds this ball is wrapped in the Micro Trax Solid Coverstock and comes 2000-grit polish with an RG of 2.470 and a Diff of 0.053 and a PSA .016.
Layout for this ball is 4x4x2
I have enjoyed when I am able to get this ball into my hands, but with bigger balls in my hand and the mid-dry I have at home I don’t get to throw this ball as much as I would like too. I keep this ball in my tournament bag and its really good when the lanes start with a higher volume or longer pattern. I can see this ball being thrown on a fresher condition with players with more hand. I am on the lower rev rate side and need the stronger balls to see the friction so with the right condition I can stay in the track a little longer than most before having to move.
BOWLER STYLE: RH - Power Stroker Rev Rate: 320 Ball Speed: 15-16 PAP: 4 7/8 right 5/8 up.

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