I am ¾ of the way through a Carbeth Cardigan, knitting double stranded, and running out of yarn… I bought the stash from someone on Ravelry and have put out a call there but with little success.
Looking for any amount of Blacker Yarns’
Blacker Swan
Worsted spun
Merino and Shetland
DK-
Dyed- Gorse
I hope someone on this wonderful forum has a skein or two somewhere in your stash. Thank you!
This is the closest I could find online with the color Gorse. Falklands?
Thank you. Yes, that’s it but they are no longer making that color. Looking for someone who has it in a stash and would be willing to part with it. 
Hopefully someone will have just what you need. Have you tried contacting the company to see if they have one or two odd skeins of the yarn color left? Fingers crossed.
This shop appears to have 6 valls available, at least it let me put 6 in a cart. Is this the right yarn?
OMG!!! You found some! WHEEE! Every single site I’ve checked has been either sold out or discontinued. Thank you so much. It wasn’t cheap (shipping price is the same as the yarn) but it saved my bacon!
I was working on that when—Thank you!—@creations found a site that has skeins still available. LOVE 
THIS GROUP! 
I just got lucky as it was the 2nd or 3rd result on a Google search. Maybe because I’m searching from the UK my results were more useful.
Glad to be able to help. Hope you managed to get enough for your project. Happy knitting!
Thank you again. You were a life saver. I only needed about two balls to finish… Because it is DK and held double, I realized with only 2 left, I wasn’t going to make the collar and button band. EEK! 
Anyway, ordered 4, just in case, and even though it may be a different dye lot, I can use the two balls I have to carry the new yarn. Hopefully that will blend the upper yoke, collar, and button bands.
That’s a good idea on blending the different dye lot. Looking forward to seeing this project and all the work and care (and expensive extra yarn) that’s gone into it.
Or maybe blend it for the yoke, then use the new for the collar and bands? Since they’re separate pieces, it will look more deliberate.
Brilliant! Thank you.