TWSBI Diamond Mini Clear Fountain Pen - Clear
The lightest Diamond Mini
The TWSBI Diamond Mini Clear takes the transparent mechanical appeal of the Diamond 580 series and makes it fully portable.  The transparent barrel keeps the pen visually alive with your ink choice, while the smaller proportions make it feel more personal.
Built around TWSBI’s reliable piston filling system and fitted with a smooth stainless steel nib, this is a compact fountain pen that still feels complete in the hand.
What sets it apart
- Compact piston filler with high ink capacity for its size
- Transparent barrel showcases ink colour and movement
- Faceted design provides structure and prevents desk roll
- Posts securely to become a comfortable full length writer
- Shares the reliable stainless steel nib from Eco
Feel in the hand
Posted, it becomes balanced and surprisingly capable for long writing sessions. Unposted, it slips easily into pockets, travel bags, sketch kits, and notebook covers.
Who it’s for
- Writers wanting a compact pen without sacrificing capacity
- Users with smaller hands who find full size pens oversized
- Travellers and everyday carry users
- Sketchers building lightweight portable kits
-
Anyone building a cleaner, more minimal writing setup
Not for
- Users who prefer large, heavier pens
- Writers wanting cartridge/converter convenience
- People who dislike posting smaller pens
- Anyone wanting a completely maintenance free writing system
Practical tips
- The Diamond Mini is designed to post securely by threading onto the back of the barrel. Most users will prefer writing with it posted for full length balance.
FAQs
Is this beginner-friendly?
Yes. The piston system is straightforward to use and the pen box includes filling instructions.
How much ink does it hold?
The chamber holds approximately 1.3mL of ink, which is still significantly more than most converter pens despite the smaller body.
How does it compare to the Diamond 580?
The Mini is shorter and more portable, with slightly lower capacity. Posted, it becomes close to a full size writer. The 580 feels larger in the hand and holds more ink.
Does the cap post securely?
Yes. The cap threads onto the back of the pen for a very stable posted writing experience.
Can you change nibs?
Yes. The nib unit is removable and replaceable.
Does it come with ink?
No. Bottled fountain pen ink is required.
Is it fragile?
Not with normal use. Avoid over tightening the cap and minimise unnecessary disassembly.
How do you clean it?
Routine cleaning only requires flushing water through the nib and barrel. Full disassembly is only needed occasionally for piston lubrication.
What’s included
- TWSBI Diamond Mini Clear Fountain Pen
- Wrench
- Silicone grease
- Presentation box
- Instruction leaflet
- Free nib tuning from LarryPOST
Ink pairing suggestions
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- Bright inks that become part of the visual experience
- Travel friendly reliable inks
- Fast drying inks for everyday note taking
Build your practice
- Use with the TWSBI Diamond Ink Well for cleaner filling
- Replacement Diamond Mini nibs for exploring line widths
- De Atramentis Document inks for permanence
Specifications
- Brand:Â TWSBI
- Brand series: Diamond Mini
- Origin:Â Taiwan
- Nib:Â Stainless steel
- Nib sizes:Â EF, F, M, B, 1.1 stub
- Filling system: Piston filler (approx. 1.3mL)
- Body:Â Transparent polycarbonate
- Trim:Â Stainless steel
- Cap:Â Twist
- Grip:Â Approx. 9mm
- Diameter:Â approx. 12mm
- Length:Â approx. 117mm (capped)
- Length:Â approx. 138mm (posted)
- Weight:Â Approx. 18g
- Comparable size:Â Kaweco Sport, Pilot Prera
Compact enough to go everywhere, but satisfying enough to make you want to keep writing once you get there.
