Autograph Authentication Report
2024 Bowman Chrome 1st Bowman Chrome Prospect Auto - Green Refractor (30/99) · #CPA-KSH
Findings
Signature comparison
This card. The signature as cropped from the slab photo (front).
Below, the known examples Crown compared it with. Examples with stronger proof (signed in front of staff, or certified by an independent authenticator) carry the most weight.
Feature by feature
| Feature | This card | Known examples | Result |
|---|---|---|---|
| Overall form and proportions | Compact two-part form: an angular 'K' followed by a looped 'S' that trails into a tight zigzag ending, with two dots above the tail. Wide and low. | R1, R3 and R5 show the same K + looped S + zigzag tail + two dots arrangement. R4 has the same parts but is taller and more open. | Match |
| Slant and baseline | Right-leaning uprights on a nearly level baseline. | R1, R3 and R5 show a similar right lean and level baseline. R4 is slightly more varied. | Match |
| Letter construction | 'K' is built from a long left-leaning stem plus an angular arm/leg stroke. The 'S' is formed with an upper loop and a long descending diagonal. | The same K construction and S loop-then-diagonal appear in R1, R3, R4 and R5. | Match |
| Connecting strokes | The K connects into its own leg stroke. The S runs continuously into the zigzag 'ijinaga' abbreviation. | Same continuous S-to-zigzag connection in R1, R3 and R5. R4 reduces the zigzag to a single large loop. | Natural variation |
| Starting and ending strokes | Starts with a short lead-in at the left of the K. Ends with a rising tapered exit to the right. Two dots are placed above the end. | The lead-in, tapered rising exit and two dots appear consistently across R1, R3, R4 and R5. | Match |
| Line quality and speed | Fluid, confident strokes with no visible tremor or hesitation at this resolution. Smooth curves on the loops. | R1, R3 and R5 show similar fluent, quickly written lines. | Match |
| Pen pressure pattern | Fairly even blue line with mild thickening at turns, as is typical of a marker on chrome. | The chrome references show a similar even, broad blue line. | Natural variation |
| Spacing | Tight spacing between the K and S blocks, with the zigzag tail compressed. | Similar spacing in R1, R3 and R5. R4 is more spread out. | Match |
| Flourishes and underlines | No underline. The only adornment is the two dots above the tail. | Same in all measurable references. | Match |
| Placement and size | Sits in the lower clear signing area above the 'Topps Certified Autograph Issue' line, spanning most of the card width. | Same placement on the 2024 chrome references (R1, R3, R5). | Match |
Measurements
Software traced the ink and measured it against the known examples. The shaded band is the signer's normal range across those examples; the gold marker is this card.
| Feature | This card | Known examples | Normal range | |
|---|---|---|---|---|
| Slant of upright strokes | -14.4° | -19.6–-12.2° | In range | |
| Overall writing angle | -0.5° | -6.2–5.9° | In range | |
| Height to width | 0.246 | 0.282–0.324 | In range | |
| Ink travel per unit width | 3.93× | 3.11–4.28× | In range | |
| Stroke thickness variation | 0.477 | 0.328–0.459 | In range | |
| Closed loops | 35 | 3.0–16.0 | Outside range | |
| Separate strokes | 15 | 2.0–18.0 | In range |
Code-based measurements compared this signature with four clean reference examples. The slant of the upright strokes, the overall writing angle, the height-to-width proportions, the amount of ink travel, the stroke-thickness variation and the number of separate strokes all fall within the signer's normal range. The one outlier is the count of closed loops, which came out much higher than in the references. That feature is easily distorted by thick marker ink and scanning, and visually the loops follow his usual pattern. Overall the numbers support authenticating the signature, with the loop count noted for a closer physical look.
Examiner notes
Ours is a 2024 Bowman Chrome 1st Bowman Prospect on-card auto (Green Refractor 30/99), signed around his 2024 debut in the Bowman product line. R1, R2, R3 and R5 are the same 2024 Bowman Chrome/Draft Chrome CPA-KSH on-card issue, so they share era, surface (chrome) and likely pen type with ours. R6 appears to be the same 2024 issue. R4 is a later 2026 Pulse Premiere card; its looser, more expansive 'K' and 'S' are explained by era and signing speed. R7 (Daily Autograph) and R8 (8x10 photo) are undated in-person/photo signings on different surfaces and are only partly visible.
How Crown authenticates autographs: the signature is compared with known examples gathered from Crown's own authenticated cards, independent authenticators and public listings, measured by software, examined by an AI forensic model, and signed off by Crown Grading staff. The decision above is Crown's.
