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Review: TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

It is not too long that I got into fountain pens. But once you start delving into that subject matter, it is really hard to not stumble upon TWSBI – a Taiwanese fountain pen manufacturer that is well known for producing great piston fillers for a really good price. That is, they basically sell them for half the price that you would normally – at least – have to pay for a piston filler. I have read a lot of good stuff about those pens on the internet. But also some not so good reviews, since they do seem to break or crack – at times. Thus, I just wanted to see for myself.

Having that said, I would like to take the opportunity to thank a great many times Frank of Fontoplumo (Netherlands) for generously providing me with a TWSBI Diamond 580 clear for a review. Frank’s been a really kind and helpful person – plus he ships in no time and the packaging’s awesome. I bet he would ship you an egg and it’ll arrive alright. So, in case after reading this review you might wanna get yourself such a pen, head straight over to his shop and treat yourself for christmas. About 60€ and it’s yours!

Enough prelude. Let’s get busy.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

The TWSBI Diamond 580 arrives in a simple brown cardboard box. TWSBI logo on top of it and a sticker with the product description on the frontside. As you can see, I got the pen in F here. I went for this nib size since I am left-handed and anything from M and upwards runs me the risk of smudging ink all over the place. None of that happens with an F, though. The nib sizes available are EF (Extra Fine), F (Fine), M (Medium), B (Broad) as well as 1,1 and 1,5mm stub.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Upon opening the cardboard box, you’ll be presented with this stylish plastic box here. I have already removed some of the protective styrofoam on that photo. Honestly, first thing that came to my mind was that the whole appearance (transparent and white plastic, rounded edges, and all that) totally reminded me of Apple straight away. But maybe that’s just me.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

When you open the lid you’ll get to the pen, which is sort of fastened into the tray with two plastic semi-circle parts – front and back. What you can already see on the picture here is the smoke gray inlay that sits inside the cap: this is to keep the nib from drying out, and I can already say that it does an excellent job in doing that. The pen writes anytime I pick it up. No hard-starts, scratching, skipping or anything like that. 

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

What is also inside the box is a short manual on how to fill and maintain the pen. Remember this is a piston filler, so you will need to have bottled ink for that. You can also completely disassemble the whole pen for cleaning and maintenance. The wrench for taking the pen apart as well as the silicon grease that you’ll need to make it ‘ink-tight’ again are also provided in the packaging.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

A frontside view of the pen shows the very springy metal clip (feels really firm – tight, but not too tight) and the glass and chrome edged TWSBI logo.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Let’s take the pen out of its tray and turn it around. On the backside sits the piston mechanism that you have to turn in order to move the piston and fill up the pen with ink. You gotta use a little force to do that (not too much though), which feels kinda alright because it also prevents you from moving the piston of the filled up pen down by accident, thus squirting ink all over the place. However, this is also the reason why I would probably not recommend to use the pen with the cap posted. Upon trying to get the cap off, you might just…well, you know where I’m going. Anyway, the pen is quite long, so posting should normally not be necessary.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

As you can see here, I’ve not promised too much. The pen is fairly large, as are my hands. Here are the specs (of the pen, not my hands):

Length capped ca. 14,5 cm
Length uncapped ca. 13 cm
Weight ca. 30 gr
Nib material Steel
Body material Transparent plastic
Ink capacity ca. 2 ml

2 ml of ink is actually quite a word. As a comparison: the regular short international cartridges contain about 0.75 ml of ink, while Lamy’s T10-catridges carry about 1.2 ml.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

It says “Diamond 580 Taiwan” on one side of the cap and “TWSBI” (just the letters in capital) on the opposite side. In order to remove the cap, you unscrew it. The screwing mechanism feels good and firm. Again, you can see the inner smoke grey cap that prevents the nib from drying.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Nib shot-time, I would say. The nib (an F, here) itself is fairly large and wide. It has some ornaments on it as well as the TWSBI-logo and -letters and an “F”, standing for its nib size, of course.

Okay come on, let’s have another one:

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

The fountain pen has a chrome trim and the plastic is facetted. The facets are not single panes running across the length of the pen, though. They are rather criss-crossed which actually reminds one of a gemstone a lot. This might actually be where the name “Diamond” stems from. But who knows. The cap is made from the same plastic as the barrel, but is smooth instead.  

Let’s have another close-up on the nib. Just because we can. This is the internet with plenty of space and I bet it won’t feel the burden of an additional photo too much.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Now, for filling the pen, as said, you’ll need a bottle of ink around.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

What you wanna do next, is screw the piston all the way down until it looks something like this here.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Then dip the pen into the ink, all the way until the ink-level rises approx. above the silver ring of the section. Then screw the piston back out. The Diamond 580 will suck in the ink from the filling hole which sits on the feed, just under the nib.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Pull the fountain pen back out and you’re all set. The TWSBI is inked! The remaining ink drops on the section might give you a clue as to how far I dipped the pen into the ink.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Look at that “florida blue” Diamine ink sloshing around in the barrel. Isn’t that fantastic?! This also maybe gives you a pretty clear idea as to why those kind of fountain pens are also called “demonstrator pens”. It really shows off that ink. Now imagine a bright orange, dark red, or whatever. Basically all the time you swap the ink, you got a different looking pen. I love that idea and do already fantasize with which color I’ll fill it up next.

I do still have some air enclosed here, but I do not mind about that. You could remove that air bubble by holding the pen up, pushing the piston to the front again (but only as far until the air is out) and then turn it back upside-down and suck in more ink. But as said, I’m good without that. Contains plenty o’ ink anyways.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Before you start writing, take a kitchen towel and remove the ink on the nib and feed, otherwise you might not have a pleasant initial writing experience.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

So let’s get to writing actually. As said – and as you can see – even though my hands are a bit on the larger side, there is absolutely no need for me to post the cap. The pen is a dream to hold and just sits there perfectly. It’s large but does not weigh a lot, which is alright. I do like heavier pens, normally. This one is not so heavy, but still really okay. The heaviest weight of the pen is removed upon unscrewing the cap, which feels pretty heavy. Again, I would not recommend posting the cap for the reasons I already pointed out. Also, I bet it’ll make the writing instrument too top-heavy.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

I have done some writing and ink-patching here for a test – and I have also used the pen on a daily basis for about a week or so now. I really love the way it writes. It is super-reliable and writes from the start anytime I pick it up. I do have to say, however, that the nib is not the smoothest glider on earth. It feels a bit ‘steely’, if I may say so. Not scratchy, though, but sort of like with a real technical precision or so. You do feel the metal-on-paper sort of. But it is not disturbing to me. It writes really well and precise and lays down an extremely sharp and consistent line of ink – almost doesn’t matter which angle you hold the pen with. No never-ending odyssey for the nib’s “sweet spot”, as a matter of fact.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

Here is a writing sample in comparison to some other pens and nibs, e.g. the Kaweco “Student” with an F nib, too. While you can see a clear difference in between Kaweco’s F (Fine) and EF (Extra Fine) nibs (2 and 3), it’s a bit hard to locate the TWSBI F-nib.

TWSBI Diamond 580 clear (Piston Filling Fountain Pen)

On a close up, I would say that the TWSBI F is pretty much exactly in between the Kaweco F and EF. But that might be subjective. I’m not sure and you may determine that for yourself from the photographs here. Of course, all that also depends a bit on the pressure you exercise on the pen while putting it on paper. For me personally, all three nibs are just exactly the perfect line thickness for me to write with, so I do not care too much about those finicky micrometers here. Think the universe :-).

All in all, I must say that I have totally fallen for this pen. It is really worth it’s money – a piston filler for around 50€ (and with that high quality) should be a no-brainer. Plus I really do love the demonstrator-character of the pen, making it an eye-catcher with the ink sloshing around in there. One downside of the pen, however, I shall not leave unmentioned: the crisp-clear transparent plastic housing of the pen really is a fingerprint magnet. If that really disturbs you, I am not sure if you should get that pen. Otherwise: highly recommended!

You may also head over to my Flickr for more shots of the pen. Enjoy and thanks for reading! 




  1. Anonymous Anonymous

    I have lost my screw top to my TWSB 580 clear pen. I would like to but another top Please direct me how I might do that

    • Scrively Scrively

      You may contact TWSBI directly

  2. Diana Ross Diana Ross

    How do you find the performance of this pen as you write a whole page?

    I’ve just gotten this pen with a 1.1mm stub and I’m finding it runs towards dry before the end of an A5 page. I have to keep twisting to put more ink in the feed. It never *fully* dries out, but I’m using sailor Yama Dori and you can tell when you’re not getting good saturation.

    I’m wondering if mine is just a QC issue or if this is the norm for this pen?

    • Scrively Scrively

      Hi Diana,
      Sorry for this experience. Sailor inks are excellent in flow, plus the pen shouldn’t run dry like that. I heavily assume a qc issue here. I had an EF Eco with the same issue. The problem is most likely ‘just’ that the tines are too tight together. That was the case with my Eco. A quick fix, if you know what and how to do. If you don’t, get in touch with where you got it from, because tampering with the nib yourself will most likely void any warranty.

      • Diana Ross Diana Ross

        Thanks for the reply! I’m glad to know this isn’t the norm for this pen. I’m fairly new to fountain pens, an so far I’m really enjoying the experience. Love your site!

        • Scrively Scrively

          Thanks a lot for your kind words! Enjoy the journey! Fountain pens are such a wonderful and enjoyable thing. Don’t hesitate to come back in case of any questions. I can also really recommend the community on Instagram or The Fountain Pen Network-group on Facebook for info and discussion

  3. Mauricio Mauricio

    I got my Twsbi Diamond 580 with F nib, yesterday and some little containers with different inks.

    I’ve tried 3 inks os far. The F nib feels rough, a bit dry and too thin for my tasting. I tried the same inks with a very old Rotring Artpen with M nib. Everything is very fluid, nothing rough, but nothing juicy either.

    So I went ahead and bought a Lamy Vista and a Kaweco Classic Sport Demonstrator, both pens with M nibs.

    M nibs with these “non-expensive/cheap” pens seem to work better for my writing and look and feel tasting.

    However, apparently, it is the Kaweco’s which perform better in my hand.

    I’ll be getting a M nib replacement for the Twsbi before getting tired of it because I do love the look and the weight of that pen.

    How about you? Have you experienced something similar?

    • Scrively Scrively

      Hi Mauricio,

      Thanks for your comment.

      Your question is a bit hard to answer without actually seeing the respective nib in person. But let me try it like this: The 580 that I had in this review was alright, the nib wrote well. As to nib width, not all Fines are equally in line width, though. This is to say, that you may find a TWSBI Fine finer than a Lamy fine. If you wish to look a bit more into that, I recommend the “Nib Nook”, which is basically a nib-width comparison-tool by the Goulet Pen Company. Quite useful, if you ask me.

      As to the dryness of a nib, unfortunately quality control of manufacturers at times is not what it should be. That is to say that it is very possible that the tines of the nib are too tight together, which results on little to no ink being able to be drawn to the writing tip by capillary action. And yes, I have had that on a TWSBI Eco. I had to open up the tines because the pen would simply almost not write. It may be, this is what you’ve experienced on your pen.

      As to the roughness (or scratchiness?), it may also be that the tines of your nib are misaligned. You may google “misaligned tines” for more on that. Also this is – sadly – nothing uncommon and may well have occurred to you.

      Hope, this helps.

  4. Prof Graeme Maxwell Morland. Prof Graeme Maxwell Morland.

    I am an architect teaching at USC. in Los Angeles, I sketch and write prolifically with my Twsbi econ, and find it one of the best most versatile pens I have used and recommend this to all my students each Semester, In all the correspondence I have read, it is unclear to me if changing the nib size, say Fine to Broad is anticipated or recommended, I have noticed that my present nib, Fine, is buried in its body to the point that you cannot read the “F” for nib size, and occasionally the nib extends out further from this point, It is easily pushed back in, but this seems unusual to me! Can you confirm if nib sizes are readily interchangeable, and if so, Can I obtain a range of nib sizes! Thanks!

    • Scrively Scrively

      Thanks much for your comment! This is indeed a great writing instrument. Yes, you can exchange the nibs. Nib and feed are just friction fit. TWSBI does also sell nib units separately: But it seems that nibs for the Eco are not available separately. I am sure, a little bit of Googleing, though, will quickly get you to a solution (compatible nibs, or the like).

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