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1329 products
1329 products
Size: 18mL
The TWSBI Classic Sapphire fountain pen pairs timeless design with modern fountain pen engineering. Featuring a deep sapphire-blue resin body accented by polished metal trim, the Classic offers a refined, understated look that feels equally at home on a desk, in a journal, or in a professional setting.
Built with TWSBI’s dependable piston-filling system, the Classic allows you to fill directly from bottled ink while providing generous ink capacity for extended writing. Its smooth, rounded shape and balanced weight create a comfortable writing experience that’s ideal for everyday use.
The pen is fitted with a polished stainless steel nib available in a variety of sizes, delivering smooth, consistent ink flow whether you’re taking notes, writing letters, or journaling.
TWSBI Spring Converter
Both Converters fit the TWSBI Swipe and any other fountain pen that accepts the standard international converter (note that size or barrel and section may need modification to fit these larger converters)
No ink inside
The TWSBI Diamond 50mL ink bottle is a glass bottle with anodized aluminum top that is the perfect accessory for any fountain pen addict! The bottle allows for easy refilling of your fountain pen by offering an upper reservoir that fills with ink when you turn the bottle upside down (cap on of course!) The reservoir provides a set amount of ink to fill your pen and avoids the hassle of dipping your pen to the bottom of the bottle, trying to get each drop out as the bottle runs low.
As an added benefit to those who own the Diamond 530, 540, 580 or Mini fountain pen you can use the colored band attachment to refill your TWSBI fountain pen without having to use the nib at all! Simply unscrew the front section of your Diamond fountain pen and attach it to the filling apparatus. Turning the piston knob of the fountain pen will draw the ink up into your pen. No more inky fingers!!
Comes in Blue, Black, Silver, Red
Please allow up to 3 weeks for back orders on TWSBI
The TWSBI Diamond 580 fountain pen blends modern engineering with classic demonstrator style, making it one of the most beloved pens in the TWSBI lineup. Crafted with a faceted, diamond-cut barrel, the 580 beautifully showcases your ink while providing a comfortable, balanced writing experience for everyday use.
Built with TWSBI’s signature piston-filling mechanism, the Diamond 580 offers a generous ink capacity and smooth, consistent flow. The transparent body allows you to monitor ink levels at a glance, while the precision-engineered stainless steel nib delivers a reliable and customizable writing experience. Designed to be user-serviceable, the 580 can be easily disassembled for cleaning and maintenance—perfect for fountain pen enthusiasts who love to tinker.
Aluminum machined grip, connector, and piston rod.
AL Models have a smooth grip section.
ALR Models have a ribbed textured grip section.
The TWSBI Diamond 580 fountain pen blends modern engineering with classic demonstrator style, making it one of the most beloved pens in the TWSBI lineup. Crafted with a faceted, diamond-cut barrel, the 580 beautifully showcases your ink while providing a comfortable, balanced writing experience for everyday use.
Built with TWSBI’s signature piston-filling mechanism, the Diamond 580 offers a generous ink capacity and smooth, consistent flow. The transparent body allows you to monitor ink levels at a glance, while the precision-engineered stainless steel nib delivers a reliable and customizable writing experience. Designed to be user-serviceable, the 580 can be easily disassembled for cleaning and maintenance—perfect for fountain pen enthusiasts who love to tinker.
Aluminum machined grip, connector, and piston rod.
AL Models have a smooth grip section.
ALR Models have a ribbed textured grip section.
Built with TWSBI’s signature piston-filling mechanism, the Diamond 580 offers a generous ink capacity and smooth, consistent flow. The transparent body allows you to monitor ink levels at a glance, while the precision-engineered stainless steel nib delivers a reliable and customizable writing experience. Designed to be user-serviceable, the 580 can be easily disassembled for cleaning and maintenance, perfect for fountain pen enthusiasts who love to tinker.
Aluminum machined grip, connector, and piston rod.
AL Models have a smooth grip section.
ALR Models have a ribbed textured grip section.
Official Release Date: August 27th 2025
The TWSBI Diamond 580 fountain pen blends modern engineering with classic demonstrator style, making it one of the most beloved pens in the TWSBI lineup. Crafted with a faceted, diamond-cut barrel, the 580 beautifully showcases your ink while providing a comfortable, balanced writing experience for everyday use.
Built with TWSBI’s signature piston-filling mechanism, the Diamond 580 offers a generous ink capacity and smooth, consistent flow. The transparent body allows you to monitor ink levels at a glance, while the precision-engineered stainless steel nib delivers a reliable and customizable writing experience. Designed to be user-serviceable, the 580 can be easily disassembled for cleaning and maintenance, perfect for fountain pen enthusiasts who love to tinker.
Aluminum machined grip, connector, and piston rod.
AL Models have a smooth grip section.
ALR Models have a ribbed textured grip section.