TWSBI Ink Bottle Diamond 50 Aluminium black

The TWSBI Diamond 50 ink bottle is far more than a simple storage vessel for ink. Crafted from clear glass with a polished aluminium cap in black, it features a clever internal plastic reservoir that fills when you invert the bottle – no need to dip all the way to the bottom, not even on the last drop. If you own a TWSBI Diamond 530, 540, 580 or Mini, you'll benefit from the integrated filling adapter: simply dock the piston mechanism directly onto it, with no ink on your fingers.

Features

• Internal ink reservoir: An integrated plastic reservoir fills when the bottle (with cap attached) is inverted. It maintains a controlled amount of ink at all times – invaluable when refilling a nearly empty bottle, as the nib never needs to reach the glass bottom.
• TWSBI filling adapter for Diamond piston fillers: Simply unscrew the front section of your Diamond 530, 540, 580 or Mini and attach it directly to the bottle's adapter. By turning the piston knob, the pen draws in ink itself – no mess, no contact with the nib.
• Glass body with aluminium cap: The clear glass body lets you easily gauge your ink supply at any time. The machined aluminium cap in black seals securely, feels pleasantly cool and smooth in the hand, and matches the aesthetic of the TWSBI Diamond range.
• 50 ml capacity: Ample supply for regular daily use; the glass vessel is compatible with most commercially available fountain pen inks.
• Supplied without ink: The bottle arrives empty – ready to be filled with any ink of your choice.

Use & Tips

• Standard filling via the reservoir: Attach the cap, invert the bottle, wait briefly for the reservoir to fill, then stand it upright – and dip your nib. The reservoir keeps the ink at a consistent level, even when the bottle is nearly empty.
• Dock your TWSBI Diamond directly: Unscrew the grip section of your Diamond piston filler, attach it to the bottle adapter, and turn the piston back. Your nib stays completely dry – ideal for quick ink changes or when travelling.
• Ink compatibility: The glass works with aqueous fountain pen inks of all kinds. For heavily pigmented or iron gall inks, we recommend a thorough rinse after emptying before filling with a different colour.
• Storage: Keep upright with the cap firmly sealed – this prevents evaporation and keeps the reservoir ready to use.
• As a travel bottle: The compact 50 ml glass format fits most desk drawers and bags; the snug aluminium cap seals reliably.

For TWSBI Enthusiasts

The reservoir system in the Diamond 50 solves a problem that piston filler users know well: in a standard ink bottle, the level eventually drops so far during refilling that the nib barely dips in and draws air before the piston fills completely. The built-in reservoir actively lifts the available ink – a thoughtful answer to the geometry of the piston mechanism. The direct adapter for Diamond models works on the same principle as a converter-dock system: the vacuum is created solely by the piston stroke, not by capillary action. This makes filling reproducible and clean, even with saturated inks that would quickly dry on the nib.

Technical Specifications