Inktend / Pen library / Diamond 580
TWSBI
Diamond 580
TWSBI's flagship demonstrator — faceted, disassemblable, and one of the highest ink capacities in its price class.
A solid mid-range option once someone has decided fountain pens are a habit worth investing a bit more into.
Specs
About TWSBI
Founded in 2009 by Ta Shin Precision — a Taiwanese manufacturer with over 50 years of plastics and metals experience — TWSBI's first pen, the Diamond 530, introduced an affordable piston-fill demonstrator that reshaped the entry-level market. This model — Diamond 580 — dates to 2013, successor to the 2009 Diamond 530 and 2011 Diamond 540.
How to fill the TWSBI Diamond 580
Unscrew the piston knob at the back of the pen, submerge the nib fully in a bottle of ink, and slowly turn the knob counter-clockwise then clockwise to draw ink in. Piston fillers hold significantly more ink than a standard cartridge — often enough for several weeks of regular writing — at the cost of being limited to bottled ink only.
Choosing a nib size
Nib size determines line width, not writing pressure — fountain pens are meant to glide, never press. Extra-fine (EF) suits small, dense handwriting and thin paper; fine (F) is the most broadly recommended default; medium (M) shows more ink character and shading; broad (B) and stub grinds favor bold, expressive strokes and calligraphy-adjacent writing.
Keeping it clean
Because TWSBI Diamond 580 holds a larger ink reserve, a full flush every 4–6 weeks (or whenever you switch colors) keeps the feed running cleanly. Inktend's cleaning reminder is tuned to a 21-day baseline and adjusts naturally to how often you actually refill.
Pairing inks with the Diamond 580
High-capacity fillers like this one are the natural home for sheening and shading inks — you'll actually see the color develop across a full page instead of running out mid-paragraph. Browse the ink library and filter by sheen.
Frequently asked questions
More from TWSBI
Specs on this page have been individually verified against manufacturer and retailer listings.