TWSBI Diamond 50 Ink Bottle – 50ml

The TWSBI Diamond 50 Ink Bottle is not merely a container—it’s a small feat of fountain pen engineering. Designed by TWSBI, this thoughtfully constructed glass bottle makes refilling calmer, cleaner, and far more civilised than the traditional dip-and-hope approach.

Although supplied empty (very much by design), the Diamond 50 features a clever upper reservoir system. Simply turn the capped bottle upside down and a measured amount of ink flows into the top chamber, ready for easy filling—no frantic angling, no scraping the bottom for the last drops. The anodised aluminium cap isn’t just handsome; it’s purpose-built to work seamlessly with TWSBI’s Diamond series pens.

Owners of Diamond 530, 540, 580, and Mini fountain pens are particularly well looked after. Using the included coloured band attachment, you can refill your pen without dipping the nib at all. Unscrew the front section, attach it directly to the bottle, and draw ink straight into the pen via the piston mechanism. Clean hands, tidy desk, and a quietly smug sense of satisfaction.

Why You’ll Love It