I learned to call them "Die-Swirl" (or DISWRL as the abbreviation) from the original "Harvey's Guide..." by Howard Herz, pg. 9 (actually captioned as "Dice in Swirl"), published in 1985.

In 1988, Borland published his "Blue Book" first edition, in which he labeled this mold as #46 (his numbering system): "Dice with Comet's Tail (6 each)", and further noted that they were a "Registered Casino Design" of Portland Card Co.

On to 1995, the "Collector's Guide to Nevada Gaming Checks and Chips", by Howard & Kregg Herz, again refers to the mold as #54 (DISWRL) "Dice in Swirl", and further notes it's by "Midwest Game Supply Co."

The MoGH's ChipGuide uses the abbreviation "Diswrl" if you want to do a mold search via the ChipGuide Query Facility, and in the "Other Stuff" geographic section, where you can look up "Manufacturers", the Portland Card Co. entry just shows sample chips on the familiar "square-in-circle" mold. In contrast, the Midwest Game Supply page DOES have numerous manufacturer sample chips with Midwest's name on them. (See 1 colorful example, from ChipGuide, below.) So it appears Herz was correct and Borland was wrong on this attribution (with the outside possibility that Portland sold it to Midwest ... but I'm going with Midwest as correct.)

Just to review the other reference books, the "Official..." book by Campiglia and Wells, 4th Edition (2009), but I assume earlier editions too, refers to the mold as "Diswirl" and further describes it as "6 dice with a 'comet's tail' ..."

And last but not least, the current edition of The Chip Rack, 22nd Edition, published in 2024, by SSS Publishing (Sands, Sarles, Spragg), also uses the description "DISWRL - 6 repetitions of dice with a comet's tail".

So there you have it. Call them Die-Swirls or Comet Dice, or something in between. Unless someone has a Midwest Gaming catalog that specifies one term or the other, I'll call it a draw.

So ... more than you wanted to know about this mold???