Yeah, they're lovely ... but not listed on the Treet website. My list above is what's currently listed. Looks like the Durasharp (Blue) in stainless and those with that lovely packaging have been retired.
Thank you for your helpful research into Treet blades.
I'm a bit confused as to what you are saying.
Here's my understanding of the overall matter:
If a Treet blade does not explicitly state it is stainless steel or platinum coated, then it is carbon steel.
If is simply says "steel," I haven't a clue. What is "Treet New Steel"? I suggest you either check the company website, or put it in a glass of water for a week and see if it rusts. (And while you're at it, place a Feather in a glass of water.)
The Razor Blades Club is a reliable, knowledgeable seller:
However, the site does not list all blades and the product descriptions are minimal. You could try asking them directly. And they have more items with more details listed on Amazon.
Note: It is "Treet Dura Sharp," not "Durasharp." The Razor Blades Club Amazon listing writes it thus for the blue blades: "Treet Dura Sharp double edge razor blades."
I use the Blue Dura Sharp blades. They are carbon steel with PTFE coating. They are very sharp and smooth, and can last five days or so, in my experience. Of course, the PTFE wears off, but the carbon steel blade is still very smooth. They are similar to the Treet 7 Days Platinum, which, in my experience, can last about a week.
I haven't ever used a Yellow Dura Sharp blade, and don't see any for sale online. I would be impressed if the Treet Dura Sharp Yellow were even sharper than the Blue - this would make them one of the sharpest blades in the world. However, the Blue are plenty sharp for most of my razors, and a bit too sharp for an Old Type. (And I already have some very nice blades that are sharper.) My guess is the Yellow are either out of production or only for sale in certain regions. I suspect if you did find an online listing showing a picture of the Yellow blades, you might get the Blue ones, as many online sellers are glacially slow in changing illustrations, and frankly don't give a damn about accurate descriptions.
I got a Treet sampler pack of 10 labels from the RBC, but I never came close to finishing it. The Dura Sharp Blue and 7 Days Platinum still seemed to be tops for sharpness and longevity, which I already was using. Some of the carbon steel blades seemed to work better in an Old Type, but sacrificed sharpness and longevity. Most of the stainless steel blades don't seem to be anything special. The first time I used Treet stainless blades many years ago, I found them unduly rough, and quickly abandoned them. However, some are better than others, and they may have improved manufacturing technology.
The Treet King blades are unusually sharp and smooth, but don't seem to have much longevity, as in one or two days. While they are a bit more expensive, the price per blade/shave is ultimately irrelevant. Does anyone else have experience with the Treet King blades in a variety of razors?
Keep in mind that there is also a brand called "Durablade," aka "Sharp," aka "Best," aka "Titanium," aka "Swiss," aka etc. They are made in Bangladesh.
And then there are the P&G "Perma-Sharp" blades. There are undoubtedly other P&G blades with similar names, though I'm about to try to catalog them without taking Dramamine. Others are welcome to try.
Please note the use of capitalization, spacing and hyphenation in razor blade names. It is important in avoiding confusion, and is especially helpful with online search engines.
Adding slightly to the mystery, there was a line of Treet razor blades made in the U.S. in the early 20th century with a similar logo. There may or may not be a connection. There is probably no connection to Treet line of canned hams, as Pakistan is a Muslim country.
Any clarifications, corrections, or contrary experiences are always welcome.
