|Eyes||Moderate arctic blue|
|Mane||Light arctic blue|
| Cutie mark|
Depiction in the seriesRubinstein is one of the nine most frequently appearing Crystal Ponies, along with "Amber Waves", Bright Smile, "Crystal Arrow", Elbow Grease, "Fleur de Verre", "Ivory", Jewel Joy, and "Night Knight".
He first appears in The Crystal Empire - Part 1 during Princess Celestia's flashback of the Crystal Empire, shown to be in the forced servitude of King Sombra. Later in the episode, he is one of many Crystal Ponies having become depressed as a result of King Sombra's curse. Hearing news of the Crystal Faire lifts his spirits and returns color to his coat and mane.
In The Crystal Empire - Part 2, Rubinstein has other forms of fun at the Crystal Faire, like watching Rainbow Dash and Fluttershy's jousting match. He helps power the Crystal Heart at the end of the episode.
In Flight to the Finish, Rubinstein appears in the stadium crowd at the Crystal Empire during the Cutie Mark Crusaders' flag-carrying audition. He also appears at the Rainbow Falls Traders Exchange in Trade Ya!, participates in the Games procession in Equestria Games, and is seen in the crowd welcoming the dignitaries in Twilight's Kingdom - Part 1.
Times are approximate.
|1||3:44 - in King Sombra's servitude; 19:17 - looking out a window next to the library; 19:25 - walking toward the Crystal Faire; 19:31 - approaching the Faire; 19:58 - walking across the Faire with Jewel Joy; 20:51 - having fun at the Faire (with several duplicates)|
|2||3:05 - in the background behind the fake Crystal Heart; 3:09, 3:27 - at the Crystal Faire; 4:09 - in front of a flower stand; 4:56 - in the background with Bright Smile; 11:42 ~ 12:04 - watching Rainbow Dash and Fluttershy's jousting match; 13:22 ~ 14:14 - in the circle of Crystal Ponies around the Crystal Heart; 14:25 - running in fear of King Sombra; 16:12 - in the large crowd of Crystal Ponies; 16:31 - watching the barrier around the Empire fall; 16:39 - watcing the return of King Sombra; 16:54 - cowering in fear of Sombra; 17:02 - watching Sombra's magic spread across the Empire; 17:30 - witnessing the return of the Crystal Princess; 17:42, 17:44 - seeing the return of the Crystal Heart; 17:49 ~ 18:01 - powering up the Crystal Heart
Duplicates: one at 4:39, 12:04, and 13:24, several at 11:42, 14:14, and 16:12
|12||3:32 - walking with Jewel Joy; 16:06 - talking with "Crystal Arrow" and Elbow Grease; 20:32 - in the large crowd of Crystal Ponies (with several duplicates)|
|13||0:45 - seen during Morning in Ponyville|
|5||20:20 ~ 21:26 - in the Crystal Empire stadium crowd|
|22||19:24, 19:42 - in the crowd at the Traders Exchange trial|
|24||4:02 - admiring Spike's crystal statue; 4:33, 4:37 - participating in the Games procession|
|25||0:19, 0:31 - decorating the Empire with Jewel Joy; 1:30, 1:39, 1:43 - in the crowd welcoming the dignitaries|
Rubinstein appears on pages 15 and 18 in the storybook Welcome to the Crystal Empire!