Okayama Denim x Japan Blue ODJB001 “Sapphire Slub” collaboration jeans review

I’ve been waiting for the second run of the Okayama Denim x Japan Blue ODJB001 “Sapphire Slub” collaboration jeans since Okayama Denim indicated there would be a re-release a couple of months ago.

Previously, I had been pleasantly surprised by Japan Blue’s JB0626 “Godzilla” jeans – reviewed here – even though they were the cheapest jeans in my collection, I had been wearing the Godzilla more than any other pair of jeans due to the superb fit and the very curious fabric. This “Sapphire Slub” jeans being reviewed today shares the same cut and a very similar weave with the Godzilla, the major difference being the colouring of the weft.

If you are interested in the background to Japan Blue, please have a look at the Godzilla jeans review linked above. Otherwise, let’s check out the Sapphire Slub!


The cut of this collaboration jeans is Japan Blue’s high-tapered cut, which is the same as that featured on the JB0626 Godzilla jeans.

To summarise from the previous review of the Godzilla jeans, the high-tapered cut provides a fairly modern, ‘lifter’s’ style fit: medium to high rise, plenty of room in the top block, fitted but not tight in the thighs, with an aggressive taper from just above the knees down to the hem.

With this cut, you could technically cuff the hem, but it just doesn’t look right given the narrowness of leg opening. I am 6’1”, and there is a small amount of stacking.

When I wear this high-tapered fit, there is a moderate amount of whiskering and heavy honeycombing.

Below is how the high-tapered cut fits after the first wash and 1.5 month of wear (Godzilla featured):


This ‘Sapphire Slub’ denim is an 18 oz sanforised fabric from Collect Mill, woven on a shuttle loom.

The warp yarns are rope dyed with pure synthetic indigo, whereas the weft yarns are dyed to the core with a blue dye. This interesting colour combination, when added with the slubby and uneven weave, is the headliner for this collaboration.

Just like the Godzilla denim, this Sapphire Slub is deliberately slubby – this is not loom-chatter, but purposefully programmed into the weave of the denim in combination with the use of slub yarns in the weft. In conjunction with the uneven warp, the resulting interplay of texture and colours is very interesting…perhaps a little overwhelmingly blue!

Due to the blue on blue colouring and the uneven nature of the weave, it is a little difficult to examine the texture on the warp side visually. The denim on a macro level is relatively hairless and starchy, feeling a little thinner and more rigid than other 18 oz denims perhaps due to the sanforisation process.

Instead of the “lakes of blue on dry land” type of aesthetic on the Godzilla jeans, the Sapphire Slub looks more like streaks of luminescent blue on a dark ocean of indigo. It is fascinating how a change in weft colouration can produce such dramatic differences in the overall look of the denim.

Expect 3% or less in shrinkage after first warm wash.


The ODJB01 is relatively well made, sewn with tonal polyester threading. The sewing is neat overall, although it lacks the more subtle details featured on higher end Japanese jeans – features such as cotton threading of different sizes and colours, or the use of extra-thick chain-stitch in the seat.

What the Sapphire Slub does better than the Godzilla though, is the fact that dual-tone chainstitch is featured, for example along the waistband where there is a dark navy/light blue thread combo.

The tonal stitching does lend to a more understated appearance, though the natural leather patch does sit in contrast with the rest of the jeans.

There are no faults that I could find. Areas of strain were nicely bartacked.

The pockets are reasonably sized. The back pockets will easily accommodate a billfold, whilst a middle wallet may poke out by 1 cm or so. The front pockets will accommodate smart phones, though the shape and the tighter opening makes it a little difficult to put my hands in them completely

The belt loops are cleanly attached, but a little on the narrow side.

The hems and seams are neatly closed.

Hardware & Peripherals

The leather patch is made with a 3 mm natural vegetable tanned leather from Tochigi tannery that is full grain with good grain growth. The logos for Okayama Denim and Japan Blue are featured. The stitching of the patch is done with tan coloured thread, in contrast with the rest of the jeans.

This patch allows for a belt to be inserted underneath, but is too narrow for my heavy workbelts.

The Sapphire Slub features Japan Blue’s antiqued brass hardware, with the buttons and rivets featuring custom embossing but plain backings. The quality of the hardware is very good, especially considering the price tier. The buttons are fixed donuts. The rivets are punch-thru with rounded heads.

Again, as with the Godzilla jeans, I would have liked to see hidden rivets make an appearance.

The sashiko pocket fabric is very interesting, and adds to the Japanese flair of these jeans, pushing the Sapphire Slub further away from reproduction Americana.


Overall, I would say the ODJB01 Sapphire Slub is a very interesting pair of jeans. It features one of my favourite fits (Japan Blue’s high-tapered) and also a cool fabric.

In considering collaboration jeans, often times you’ll find that dealers or retailers may simply change the cut or minor peripheral details, making it more of a marketing exercise or to cater for local flavours…but the Sapphire Slub is an earnest collaboration, going as far as changing aspects of the denim itself.

The construction is basic but clean, without significant flaws or faults; the tonal, dual-coloured stitching is a nice touch.

The denim itself pushes the boundaries of what purists would consider to be workwear denim, and as such this offering from Japan Blue is firmly placed in the Japanese tradition rather than having too much to do with Americana, besides it being a pair of jeans. I really like both the Sapphire Slub denim and the Godzilla denim and at $180 USD each, I believe that they are the most interesting Japanese denims available in the <$200 USD price bracket.

It remains to be seen how this Sapphire Slub denim will age in the long run – limited examples may be viewed at r/rawdenim. But if the Godzilla denim is anything to go by, the Sapphire Slub will fade relatively quickly.

With all this praise, I must say that there is perhaps room to improve. Hidden rivets would be a welcomed addition. Further, thicker & raised belt loops and a variation in thread sizing would really enhance the detailing and geek-factor for these jeans.

All in all, the Sapphire Slub is very cool collaboration between Okayama Denim & Japan Blue that would appeal not just to new comers to the denim hobby but also more seasoned denimheads who are interested in unique fabrics or coloured wefts. The Sapphire Slub is sleek, nicely cut, neatly made and you get a lot of Japanese denim for what you’re paying.

I am really looking forward to seeing how the Sapphire Slub will age, but also I’m excited about future releases of this high-tapered cut in other cool denims too.


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