I've been working on these for a while now, and while they are by no means complete yet, I figured I'd post what I have so far. I will be adding conversions for the other Mill Hill shapes and sizes, conversions FROM Delica to other brands, etc, as I purchase more sample cards in future. Currently, these only include Mill Hill Seed Beads - or size 11/0.
First, I'd just like to mention - Mill Hill does NOT manufacture beads themselves. They use (from what I can tell) Toho and Miyuki for their suppliers. For example, Mill Hill Magnifica beads are Toho Treasure Beads (NOT Delica beads as some suggest). In some cases, they even use the same colour number.
There are separate conversions for Miyuki and Delica, even though they both come from Miyuki, because Miyuki uses a different numbering system for each type. Silly, but true. Toho, on the other hand, uses the same numbering system for ALL their beads - Treasure, Aiko and round.
To do these conversions, I tried my best to convert bead to bead from samples on hand. In some cases my colour cards are incomplete, however, so I did have to rely on other conversion charts or pictures on the internet, so where in some cases they are very accurate (exact), in other cases they may be close but I'm not positive.
I only listed what I felt were exact or really close matches, really close meaning either the same colour with a similar finish, or the same finish with a similar colour. For example, an opaque lustered bead is similar to a ceylon bead so if I couldn't find a comparable ceylon but could find a comparable lustered, I used that. However a ceylon isn't remotely close to a silver lined bead, so I didn't bother listing those. I hope that makes sense?
Rather than just list the numbers, I added the colour descriptions for each one. Of course Miyuki and Toho don't actually name their colours, only by number, so I got the colour descriptions from suppliers I order from frequently - for Miyuki, I used Caravan Beads or Charisma Beads. For Delica I used Caravan Beads, Fusion Beads or Artbeads. For Toho I used Bobby Bead or Artbeads. Why? Because some people may not be as picky as me when it comes to using a converted colour, and close is good enough. You may be happy with choosing the same colour in a different finish - so this makes it easier to find that.
Why would you need a bead conversion anyway? Let's say you want to stitch something on a different count of fabric than what's called for but you still want to use the same colour bead. You need Mill Hill colour 02001, but you want them in size 15 (petite) to fit 36ct or 40ct fabric. Well Mill Hill doesn't have that colour in size 15. But Miyuki and Toho do. Which is exactly why I started this project - I don't stitch on 28 or 32ct if I can help it. But I like stitching Mirabilias and Chatelaines and the like that have loads of beads, I just want to stitch them on 40ct. So I started comparing and converting for myself for designs I planned to stitch and figured I might as well go all the way and convert the whole lot, right? Or perhaps, like many people, you just don't like the irregular nature of Mill Hill beads and you prefer the more consistent cylindrical Delica, Treasure or Aiko beads, so you'd prefer to use those.
So without further ado, here's what I have converted so far:
Mill Hill to Delica
Mill Hill to Miyuki
Mill Hill to Toho
Hope they're helpful!