Separate the body from the contact surface
The nib body is the shaped metal component held above the feed. On many fountain pens, a harder tipping alloy is attached near its end and ground into the writing surface. Gold content describes the body alloy, not automatically the tipping. A gold-coloured nib may be plated steel, while a pale nib may be rhodium-plated gold. Colour alone cannot settle the question.
A 14K mark indicates nominal gold fineness of 14 parts in 24; 18K indicates 18 parts in 24. The corresponding fineness marks commonly seen are 585 and 750. These are material claims, not measurements of flexibility. Geometry, thickness, heat treatment and overall construction matter. Two 18K nibs can feel quite different, and a steel nib can provide excellent alignment and a polished writing surface.
Be careful with the word “iridium”
Collectors often use “iridium” as shorthand for tipping. Actual compositions vary and can include other hard, wear-resistant metals. Unless the maker provides a specification, do not infer a precise alloy from an imprint or a traditional phrase. Some nibs are untipped, including certain folded-tip designs and italic constructions. Their paper-contact surface is formed differently, so first establish what you are inspecting.
The shaped alloy sheet; its design influences stiffness.
The split leading toward the point; alignment matters at contact.
The harder material ground into the writing surface.
The component that supports ink delivery and air exchange.
Compare observable characteristics
| Description | Useful evidence | Not established |
|---|---|---|
| Steel body | Body material, if documented | Smoothness, ink flow or flexibility |
| 14K / 585 gold | Nominal gold fineness | A particular softness or grind |
| 18K / 750 gold | Higher nominal gold proportion | Better writing than a 14K nib |
| Round tipping | A rounded contact geometry | An identical line in every ink and hand |
| Stub or italic | Directional line variation by geometry | Flexibility under pressure |
| Fine / medium / broad | A maker’s width category | A universal measured line width |
Observe before applying pressure
Use good diffuse light and modest magnification to examine the point. Look for a visible mismatch in tine height, damage or contamination. Viewing angle can create misleading impressions, so inspect from more than one direction without touching the tipping. A loupe is an aid, not a licence to bend the nib. Do not spread the tines to test flexibility, especially on an unfamiliar collector edition.
Nib names also need context. Sailor, Pilot and Platinum each use their own product ranges and width conventions; a label shared across brands is not a calibrated measurement. JoWo and Peter Bock supply nibs used by other pen makers, but a supplier name alone does not tell you the final tuning, feed configuration or quality control applied to a complete pen.
Describe the line and the conditions that produced it. “Smooth” without context is only half an observation.
Make a controlled writing sample
If the pen is safe to fill and its owner permits use, choose an appropriate fountain pen ink and familiar paper. Note the ink, paper, nib marking, writing angle and whether the pen was dipped or filled. A dipped nib may behave differently from one supplied continuously by its feed. Keep hand pressure light and use ordinary words, loops and gentle directional strokes.
Record hard starts, interruptions and directional catching separately. Audible or tactile feedback is not automatically a fault; it differs from a sharp catch caused by a problem. Paper coating, ink lubrication, dried residue and rotation of the pen can all change the result. Repeat a cautious test under the same conditions before drawing a conclusion. Stop if the point appears damaged or the pen leaks.
Preserve the history of adjustment
A specialist regrind can make a pen better suited to its owner while departing from its factory specification. Record who performed the work, what was requested and any supplied measurements. “Medium” stamped on a nib no longer fully describes it after a custom grind. Keep before-and-after writing samples if available, and disclose the alteration in future descriptions.
For model-specific information, consult Sailor, Pilot, Platinum, JoWo or Peter Bock as appropriate. General material knowledge helps frame a question, but the complete writing assembly—and the individual example—still deserves inspection.