- Who
- Mitsubishi Pencil Co., Ltd.
- Where
- Japan (Shinjuku)
- When
The blackest gel ink ball pen is uni-ball one produced by Mitsubishi Pencil Co.Ltd. (Japan) which measures 5.96 (Y value) in tests performed by Suga Test Instruments Co., Ltd. in Shinjuku, Tokyo, Japan on 7 June 2023.
The test was conducted at Suga Test Instruments Co., Ltd. using a testing apparatus "Colour Meter SC-50μ".
