Chinese tamahangane katana

Tamahagane, as I understand it, can only be applied to products from japan because it is dependant on the specific iron sand and manufacturing process.
It depends what the chinese "tamahagane" really is. EDIT: It could be a real reproduction, step by step. Could be something tht only looks like tamahagane. In the end all of these can be equally bad or good depending on the smith. If the smith, as you say, is more famous for quality, it likely is a usable sword as any other.
Good tamahagane can be used to cut, but hard targets (bone for example) are not something you want to cut with any sword - of course depends what you see as "hard target".

It's true that the Chinese can buy authentic Tamahagane ore and make a sword, but this is very rare. When they do, its usually the same price as a bespoke tamahagane sword from Japan. I would think that the polish would be inferior, though I've seen some decent polishes accomplished in China.

What is called "tamahagane" most of the time though is probably something like a 1075 or 1095 edge, a wrought iron core, and probably a mild steel or some kind of relatively soft carbon steel on the outside (to make the shinogi). That makes it relatively easy to polish so that it looks authentic-ish. All these would be made using standard Chinese pig iron though, then processed via different traditional processes to get the desired final steel/wrought. Still, they are pretty nice, and I have several bare blades like this. They polish up traditionally quite nicely, differentially harden well, and they look really good. They work best with a pretty plain hamon though, like a suguha. If they use some other kind of hamon, the acid polish doesn't always work out well. Still, you usually get defects in the geometry of some kind, with the most common being a weird tip (kissaki), or habaki.

If they want it to look like "damascus," they usually fold various standard steels together, but they don't usually call this "tamahagane," its usually called san mai or something like that.

Either the authentic tamahagane or the imitation "tamahagane" would be suitable for cutting, but I agree you want to avoid hard targets. They should cut intended targets well, but every time you're cutting you still run the risk of breaking the sword. A laminated sword (made from different layers of steel) is always more likely to come apart than a mono-steel sword, and a sword with gaps in the laminations (as an authentic tamahagane sword or a wrought iron sword) further increases the risk of breakage. Further, differentially hardened swords in my opinion have a further slightly elevated risk of breakage compared to through hardening, because there are different forces going through the soft and hard steel, stressing the area between them. Still, a laminated, differentially hardened sword is considered more desireable aesthetically.

So given all that, usually I'd avoid cutting with a sword meant for aesthetic purposes. That doesn't mean they can't do it, but also don't be surprised if and when they break. The higher your skill though, the less likely this is to happen, so usually we recommend picking up an inexpensive, through hardened monosteel sword for practice. Once you're pretty proficient, then it makes more sense to risk breaking your expensive sword.

Real Japanese Tamahagane can be bought for something like $100-200/kg. I'm sure it will vary by grades and off the top of my head, I think you need about 10kg to forge a sword from what one American smith told me. Maybe it was just 10lbs but there was quite of loss from material to finished blade.

While this is not cheap, this is still a fraction of the base cost of a Nihonto from Tozando (though they take their cut but most swords go through a broker anyways rather than buying directly from a smith [as many wouldnt make saya, or carve/wrap tsuka either]).

I did this exact thing. There is only one source for international buyers, and that is kameya. It's not a money making proposition for the Japanese, bacause harvesting iron sand, making coal, and making the tamahagane is so labour intensive, so the government reserves some of the tamahagane they make, and international smiths can buy it so that the cultural practice of forging it is preserved.

For first time smiths, they recommend a 30 kilo package. This includes tamahagane, but also some of the lower quality bits of the kera. These are not useless though, you can use them to make the core steel, and also higher carbon steel that's useful for going around the blade (the more carbon, the more activity and interesting features like Nie). The cost for these 30 kilos, including at least 10 kilos of tamahagane, is about 45,000 yen.

The shipping from Japan to Canada is also very expensive. They can load it on a ship, but I don't recommend this. It is minimum 3 months to get it, but it could be a year, and it could be never. At this weight, the price difference between EMS and airmail isn't much, so it makes sense to use EMS. The cost for that was about 60,000 yen.

So that's the minimum you can pay for enough tamahagane to make a sword in 2024. I'm sure the price is similar in China, which is why I've never seen a real tamahagane Chinese blade less than about $5000. I've seen imitation ones between $1000 and $5000, but never the real deal.

Edit: I should clarify that the 30 kilos, even though not everything is "tamahagane" can probably be used to make about 2-3 one kilo swords. The kera has some bits that are mostly charcoal, but some bits that are virtually mild steel. The bits that are mostly charcoal will take a bit of work (very crumbly), but these can be used alone, or mixed with the tamahagane to make cladding steel, and the mild steel can be worked relatively easily compared with both other parts, to make the core. The mild steel is probably more than 10% usable, but the high carbon kera is probably less than 10%, so it evens out in the end! You can make a whole blade out of tamahagane, but in my opinion that's a waste of good material and time. Don't forget though that you'll also need a lot of propane or a mountain of soft wood charcoal.