Jem Comics

Jem comic books (they are about 8 X 11", not typical comic-sized) appear to have originated in the UK, published by "London Editions Mazazines, an Egmont Company" in 1986 and 1987.  They were reprinted in various languages and sold throughout Europe.  Many Hasbro toy lines received the same treatment (My Little Pony, for example).  To my knowledge, there are 12 Jem UK comic books, and 2 special editions.  There is an image of issue #13 shown at the back of issue #12, but I'm not yet certain if it ever actually made it to print.
They were printed on newsprint and came out bi-weekly, 24 pages long, features 2 original stories as well as ads for the Jem dolls, and a couple unrelated pages.  The specials were about twice the size.
I haven't seen all editions of all the comics yet, but the German ones definitely did not follow the same time line as the UK comics (eg. the 2nd UK story didn't appear in Germany until their issue #4)  Italy appears to have followed the same time line as the UK, but had thicker volumes on higher quality paper.
They do have a few ties to the Jem annuals, the first being and ad in the comic for the Jem annual.  The second link is questionable since I have only seen the one UK comic, but the #11 German comic (thought to be directly translated from the UK ones) actually contains stories and art from the 1988 Jem annual.  Whether the #11 UK comic was just parts of the 1988 Annual as well, or if the #11 German comic was exclusive to Germany is still unknown.  It could be the comics were more successful in Germany and they needed material to use for future issues.

Thanks to Laura (Badgerprincess) for much of the comics information included here (as well as the scans!) 
Thanks to Isabelle for the French comic book information and photo. 

Cover UK Issue # Story Title Story Synopsis German Issue Italian Issue French Issue
1 Has Been Jerrica helps a has-been songwriter, by performing his songs (as Jerrica...  with Aja playing the flute!) in concert. 1 unknown unknown
1 Look Out World, Here we Come Jerrica, Rio and the Misfits commence their world tour (Jerrica with a special make up purse that helps her transform into Jem over great distances O_O). 4 unknown unknown
2 4 (probably) unknown unknown
2 4 (probably) unknown unknown
3 1 (probably) unknown unknown
3 1 (probably) unknown unknown
4 The House of Fear Jem & The Holograms go to a "haunted" mansion to film a Christmas video, and people start disappearing. 2 Issue #2 Rock Parade, French title: "La maison hantée"
4 The Kidnappers Strike Again Eric Raymond is abducted by the Paris kidnappers (he stiffed them in the last story about them) and Jem & Co. have to bail him out. 5 Issue #2 unknown
5 Big Top Pop Jem and the Holograms play a benefit concert at a circus. The Misfits attempt to foil them by posing as clowns and sabotaging the show. 2 Issue #2 Rock Parade, French title: "Rock Parade"
5 Chaos in Capri The Holograms & The Misfits are invited to an Italian director's villa, in order to do a musical number in his film. When Jerrica goes swimming and loses her earrings, she is arrested on suspicion of kidnapping when Jem's whereabouts can't be accounted for. 5 Issue #2 Le Trésor Des Pharaons, French title: "Quiproquo a Capri."
6 The Greatest Gift Money is tight at Starlight house and the girls need to make money to pay the electricity bill.  They meet a country star on a TV set who pays for bill when one of the orphans manages to cheer up his bereaved daughter. 2 Issue #2 unknown
6 The Goddess Diana 5 Issue #2 Le Trésor Des Pharaons, French title: "La déesse Diane."
7 The End of the Road 3 unknown unknown
7 The Treasure of the Pharoahs 6 unknown Le Trésor Des Pharaons, French title: "Le trésor des pharaons"
8 On the Road to Rockville 3 unknown unknown
8 Seeing Is Believing 6 unknown unknown
9 Scandal in Sydney 6 unknown Le Trésor Des Pharaons, French title: "Scandale a Sydney."
9 Hidden Message 3 unknown unknown
10 Springtime in Paris 7 unknown unknown
10 The Misfit 7 unknown unknown
11 Rock And Run 7 unknown unknown
11 Dog and Bones 8 unknown unknown
12 Record Shop Rumpus 8 unknown unknown
12 The Show Must Go On 8 unknown unknown
13 unknown, this issue may have never gotten to print
Special #1 Opportunity Knocks unknown, but most likely #9 unknown unknown
Special #1 Day of Disasters unknown, but most likely #9 unknown unknown
Special #1 Rio to the Rescue unknown, but most likely #9 unknown unknown
Special #1 Wonderland 10 unknown unknown
Special #2 Cruising 10 unknown unknown
Special #2 Monkeys And Misfits 11 unknown unknown
Special #2 Fantastic 10 unknown unknown
Rock Parade, "Qui est qui" (Who is who; a story similar to "One Jem Too Many, but didn't appear in the UK comics)
Rock Parade, ""Un manager de haut vol" ( (High-flying manager) (Another story that may not have been in the UK comics!)