TWSBI Diamond 580 RBT Fountain Pen

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The TWSBI Diamond 580 matches superior craftsmanship with distinctive design, creating a writing instrument every pen aficionado will covet. The striking diamond faceted barrel prevents your pen from rolling off the table, whilst the transparent construction allows you to see the piston fill workings and remaining ink levels. Sitting comfortably in the hand, this durable, lightweight fountain pen is finished with a screw-close cap and rubber O-ring to prevent leaks and drying. Match the Diamond 580 with the TWSBI Diamond Ink Bottle for an easy, fuss free filling experience. All TWSBI fountain pens can be disassembled for cleaning and maintenance. TWSBI includes the tools to do so, but recommend this is only carried out by experienced fountain pen users. This should only be carried out as part of long term servicing of the pen; it will not need to be done straight away. All disassembly is carried out at the owners risk!

Key Features

  • Transparent body with red cap and grip & blue mechanism twist tip
  • Polycarbonate construction creates scratch resistant, resilient and crystal clear finish
  • Diamond faceted barrel
  • Twist action piston fill mechanism
  • Stainless steel nib with intricate TWSBI logo and detailing
  • Screw close cap
  • Rubber O-ring prevents leakage and drying
  • Gently tapered grip section
  • TWSBI logo button on end cap
  • TWSBI presentation box
  • Lifetime manufacturer warranty
  • Dimensions (Closed): L 120mm x D 13.5mm
  • Dimensions (Posted): L 142mm x D 13.5mm

After 40 years manufacturing for other well know brands, TWSBI started their own range of pens. Their fountain pens use innovative piston filling mechanisms (such as springs and vacuums) that make it quicker and easier to fill the pen with ink. Designed with transparent bodies so you can see the inner workings of the pen, TWSBI supply a toolkit with every writing instrument so you can take it apart and clean thoroughly.

Delivery Information

All orders placed before 3pm Mon-Fri are despatched the same day (except on a bank holiday), even if your order has personalisation. Orders placed after 3pm, at the weekend or on a bank holiday are despatched next working day.

UK: We use a Royal Mail tracked service. Standard delivery is free (£2 charge for orders under £10) and takes 2 to 5 working days, Premium is £3 and takes 1 to 2 working days. Next working day is £6 and is delivered by 4pm (requires a signature).

International: We delivery worldwide with a standard and express service. Please visit our international website

Returns Information

If you are unhappy with your items, they can be returned to us within 21 days of receipt of purchase to be eligible for an exchange/refund. The item must still be in a re-saleable condition and returned with proof of purchase. Items that have been personalised cannot be returned unless they are faulty. Items purchased for Christmas can be returned by 14th January for a refund, as long as all our other returns criteria are met

Should you receive a damaged or incorrectly dispatched item, please inform us within 7 days of receipt, so we can advise you on the return of the item. Call 0208 731 8610 or email If a faulty or incorrect item is returned, we will refund your postage up to the cost of 1st class recorded Royal Mail. If you are sending items from abroad, please call us for a delivery quote

This is why people love it

Loads of good customer reviews submitted through feefo

  1. Written on 27-Sep-2021
  2. Written on 22-Jul-2021
    I love this pen with the 1.1 nib. My new favorite. Also, I really wanted this color combo and couldn’t find it in the U.S.
  3. Written on 07-Jun-2019
    Absolutely a beautiful fountain pen. Since renewing my love for “snail mail,” I discovered the art of writing with fountain pens. (Trust me, you won’t go back to ballpoint!) TWSBI is one of my personal favorite brands and finding this gem still on the market was a bonus. The TWSBI Diamond RB fountain pen is a well constructed, demonstrator FP with beautiful chrome detailing, highlighted with its trademark piston filling mechanism that holds a considerable amount of ink. I’m not a fan of bold thick lines, so I choose to write with an EF nib. I have yet to have any issues with skipping or scratching while writing (w/any of my TWSBI FPs..), in fact, my writing is smooth, light and thoroughly enjoyable. No hand cramps - and that’s a plus. I would highly recommend ANY TWSBI to anyone diving into this craziness called fountain pen mania. The cost and construction is far greater than many well known brands. Enjoy and happy writing. PS... I also use for sketching!!
  4. Written on 30-May-2019
    my favourite Easy to maintain and nice filling action.huge ink capacity
  5. Written on 01-May-2019
    Nice pen - works well. Not as smooth as some of my other pens but writes well and good flow out of the box.
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