My Gamma Sapphire 1.28 Review
Which gauge did you receive: 1.28
Tension(s) used for playtest: 48/45
Regular string setup: Solinco Confidential 1.20, 48/45 pounds
Racquet used for test: Babolat Aero 112
I recorded some video of my session against a ball machine using Sapphire 1.28 at about the three hour mark. Apologies for the poor and crooked aim.
Power/Control of test string:
I typically prefer stiffer, thin-gauge, low-powered poly strings so I found Sapphire to have considerably more power than my usual string, and would rate it as more powerful than the average poly string in general. It was easy to generate high levels of ball speed on ground strokes and serves, and volleys only required clean contact to generate putaway pace.
Despite the high power levels, control was very good. Directional control is very consistent in both aim and launch angle, and there was never a hot spot on the string bed where the ball seemed to come off with unexpected speed. It was also more easy than expected to take speed off the ball, making drop volleys relatively simple to execute.
Sapphire has a consistently high launch angle for a round string that is more typical of a moderately shaped and/or thinner poly string. However, the launch angle doesn’t increase as significantly as a shaped poly string as the swing becomes more vertical. This makes height control more dependent on racquet face angle rather than the degree of the vertical component of the swing.
Feel (Stiff? Mushy? Muted? Crisp? Comfortable?):
Sapphire has an elastic, lively feel that provides good pocketing sensation without feeling mushy. Contact provides a crisp feel without harshness. Sapphire is also among the more comfortable strings I’ve tested and it gives the sensation of increasing the size of the sweet spot. Mis-hits near the frame generate much less shock than other poly strings. It is rare that a string can feel powerful and comfortable, but still provide good feedback on impact and Sapphire does that very well.
Spin:
Sapphire is one of the more spin capable round strings I have tried. When the string bed is fresh, the high launch angle adds to that impression. The actual amount of spin generated is a bit less than I can get from my normal 1.20 Confidential but still enough that I can play my normal game and not notice any deficit in being able to hit the shots I want. As a moderate topspin player who only occasionally hits heavy topspin but frequently uses heavy underspin, Sapphire has enough grip on the ball to easily reverse the spin after the ball bounces, and even a flat stroke trajectory generates a few rotations of topspin.
I did notice the lesser spin generation most when serving. In the deuce court trying to hit a wide slice serve, the ball would curve less in the air and after the bounce. However, the lower launch angle tends to make the ball land wide of the sideline so these two factors canceled each other and overall required minimal adjustment to hit my spot.
Serving from the ad side, I normally try to bounce the ball as high as possible to a righty backhand and it was here that my serve required some adjustment. Second serves tended to land more towards the middle of the box so I deliberately aimed for the middle of the doubles alley. I still got good bounce height on second serves.
Sensitivity to incoming spin is low and typical of round strings. I only had to make minimal adjustments when volleying heavily spun balls.
Playability Duration (did you notice changes in feel and performance over time?):
I tracked tension loss using RacquetTune from immediately after stringing, to sitting overnight, and after each playing session. Total tension loss over about 15 hours of play was 21%, with the string notched about half way through after that 15 hours of use. Unlike many other poly strings which have the majority of their tension loss in the first few hitting sessions, Sapphire had a little bit of tension loss over several sessions before further tension loss minimized. This made the string bed consistent and easy to adjust to from session to session.
The only significant change came at around the three hour mark when notching first began. Launch angle and spin generation both decreased a moderate amount over the course of one hitting session but stabilized afterwards.
Sapphire retained its playing characteristics through the entire time I used it. The elastic, lively feel was still there at 15 hours. Spin capability was still decent despite the ball contact surface wearing flat. And Sapphire never lost that comfortable, plush response.
I only noticed two issues near the end of my playing time. First is that as tension loss approached and exceeded 20%, I felt a loss of precise control and had some balls fly on me. Second was that it took a committed swing for a normal launch angle and spin generation. If I decelerated into the contact point, the ball would slide off the strings and would go into the net.
Tension Recommendations (would you string it differently next time - why?):
I purchased the two promotional packs of 1.28 Sapphire and restrung at 51/48 versus my usual 48/45. The higher tension lowered the launch angle a slight bit but all of the other positive aspects of Sapphire were still there. I’m at about the six hour mark with this second string job and am finding it to be equally playable. With both stringings, I performed a light prestretch to remove coil memory, and then used a double pull on a lockout machine to remove the initial tension loss. Based on this, I would recommend stringing a couple to a few pounds tighter than with other poly strings, and using either a slow pull or pulling to above tension and then relaxing back to reference tension.
List any additional thoughts (optional):
Despite doing a light prestretch, coil memory was still moderate. Weaving the crosses showed average or slightly greater than average inter-string friction which led me to believe the string would have minimal movement and low launch angle during play but that wasn’t the case.
Overall, Sapphire 1.28 is an excellent round string that combines a lively, elastic, powerful, and comfortable response with a crisp feel and very good control. Sapphire ages well, with gradual performance changes that won’t require major adjustment or compensation from session to session.
As an older age group competitor who relies less on heavy topspin every year, this is a string that I could (and may) switch to from my current 1.20 Confidential. Sapphire would be an excellent upgrade for any poly string user who would like more comfort or power while retaining or increasing spin capability compared to other round strings. It would also be an excellent choice for a first time poly user.
Thanks to Gamma and Tennis Warehouse for allowing me to test Sapphire.