Totsy
Chances are if you have a knock-off Jem fashion, it was made by Totsy.  They are the manufacturers of the Jewel line of fashions, mostly recognizable through their shoes which are quite similar to Jem's, distinguishable most easily by having two small holes on the soles.  I've not yet seen a Jewel doll herself, if she exists.  One of the better knock-offs IMHO, as the shoes fit and the styles are rather creative and of the era.  Totsy seems to be the maker of both Sears and JC Penney's knock-off bulk catalogue fashions.
In typical waste-not-want-not fashion, Totsy also slapped stickers on their old stock of Michael Jackson-esque fashions from 1984, stating they could be worn by Jem and the Misfits.  Yes, they were androdgynous days, those 80's.
I have given the outfits some names, just for brevity's sake.  I do not know if they ever had proper names assigned to them by the company.

Big thanks to Liz Pemberton for basically ghost writing this page for me and providing nearly all the photos of the loose items!  Also thanks to Marilyn who gave me the vast majority of the MIB pictures used in this section.  
Space Girl
Bodysuit, skirt; gold lame and tights.  I have seen two versions of the bodysuit, the paler one being more common.  I have also seen this fashion with a hollow white plastic guitar. 
Pumps; pale blue. 
Rainbow Overalls
Came with shiny multi-coloured overalls, red blouse with oversized button and dark blue pumps (holes in the soles). I have also seen this fashion with a hollow red plastic guitar.  It appears that there may be a variant of the overalls (stretchier sparkly material).  The 1986 JC Penney Christmas catalogue shows this outfit, or one similar to it in their "Starr fashions" knock off line. I have also seen this fashion with a hollow red plastic guitar. 
 
Fringe Royale
Came with shiny one-sleeved purple jumpsuit with yellow fringe, yellow fringed armband, purple choker and yellow shoes. The 1986 JC Penney Christmas catalogue shows this outfit, or one similar to it in their Barbie knock off line, paired with a keyboard. 
Silver & Gold
See close up. Also included white pumps.  A variation of this fashion was sold in one of the 20 pc Gift Sets.
Dream Coat
This fashion also can come with a more lavender/paler jacket.
Jade Jumpsuit
This fashion has been seen with two different shades of green jumpsuits.
Photo needed Brown & Yellow fashion
Batwing-sleeved large yellow sweater, bright yellow top, brown skirt, white lace tights, yellow shoes, "walkman" accessory.
Night Life Fashion: Golden Stripes
Hair decoration and purse not shown.  It looks like one of the fashions shown in the Canadian Sears 1987 Wishbook.
photo needed.  Night Life Fashion: Black & Blue Rik Rak
Aqua Lame dress, one black sleeve with matching black hat, white cape, dark blue shoes.
photo needed Night Life Fashion: Black & Gold & Faux Fur Stole
Column dress with gold lame one sleeved tank bodice, sparkly black skirt, white fur stole, hair decoration and black shoes.
Gift Set: 20 Pc Set #1 (Pink, Gold & Green)
The Pink fashion is very similar in style to a JC Penney knock off fashion.
The Gold fashion is different fabrics but the same pattern as a Sears knock off fashion.
Photo needed. Gift Set: 20 Pc Set #2 (Gold, Blue & Pink)
-Gold and silver fashion, similar to this one which was previously sold singly.
-Sparkly blue and silver minidress & tights
-Pale pink sparkly one-sleeved top with white satin & silver pink pants (I think they are pants?!)  
-3 pairs of shoes, white, blue and pink.
Gift Set: 20 Pc Set #3 (Blue, Gold & Black)
From the Sears Canada 1987 Christmas catalogue.  I do not know if these were packaged for display or merely sent in cardboard mailers.  The fashion in the middle worn by Jem looks very similar to one of the Night Life fashions previously sold separately.  The other two I am not familiar with. 
There are also several Barbie-sized rock star Totsy fashions that may be used with/be confused for Jem knock offs which I may get into later!
Super Star Fashions
Made for the Michael Jackson doll, c. 1984. (I have not seen any for female dolls yet).  They were not made expressly for Jem or Rio, but later bore stickers with the Jewel image reading: "Made to fit 12 & 1/2" dolls: Jem, Jewel, Rio and the Misfits" to entice Jem or Jewel shoppers.  Interestingly, if you lift up this sticker, it reads "Made to fit 12" Boy Dolls; Elvis, Ken, Michael Jackson."*  Some fashions came with only one glove, predictably.  In a pink box, with 3 male rock stars graphic. They are all men's clothes, despite the wishful thoughts that the sticker may give you.
 
  • Black sparkly jacket w/sparkly white pants, socks, one glove (etc.) 
  • Sparkly black shirt, w/maroon/white tuxedo (can have either black or white rik rak) 
  • Red satin jumpsuit 
  • White sparkly blouse/pants, etc. with silver vest 
  • Pink satin jacket w/gold pants. 
  • White outfit with tinselly-gold vest, accents (shown right - thanks to Sonia for the pic) 
  • Shiny leatherette black pants and vest (w/brown), white shirt. 
  • Pink ruffled blouse with hot pink shiny bowtie, silver vest and glove, hot pink shiny pants, pink socks and sunglasses.* 

    • * This information and photo courtsey of Janice 

    Super Star Accessories (Smaller, on bubble cards w/pink background, with 3 male rock stars graphic) 

  • Red jacket, gold vest outfit. 
  • blue shiny jacket w/white dickie outfit 
  • white long-sleeved shirt w/yellow vest 
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