How do I know a Gunnar Henderson signed baseball is real?

Buy certified, and verify the certificate yourself rather than trusting the listing photo of it. There are two families of certification. First, MLB Authentication — Major League Baseball's own program, where an authenticator witnesses the signing and applies a tamper-evident hologram with a unique serial number you can look up on MLB's authentication site. Second, the third-party authenticators: JSA (James Spence Authentication), PSA/DNA and Beckett Authentication (BAS), each of which issues its own numbered sticker or hologram plus a certificate, lookupable on the authenticator's own site. An uncertified ball with a seller's homemade 'certificate of authenticity' proves nothing — anyone can print one.

What's the difference between MLB Authentication and JSA or PSA/DNA?

MLB Authentication is witness-based: an authenticator was physically present when the item was signed or used, so the hologram documents a chain of custody. Third-party authenticators like JSA, PSA/DNA and Beckett usually work by expert opinion — a specialist examines the signature and certifies it as genuine — although they also witness organized signings. Witnessed items (MLB hologram, or a 'witnessed' third-party sticker) carry the strongest provenance; opinion-based certification is still widely accepted, but is an expert judgement rather than an eyewitness record.

Is a signed 'authentic' jersey different from a signed replica?

Yes, and the jersey itself drives most of the price difference. An authentic (on-field-spec) jersey is the same construction a player wears; a replica or fan jersey is a cheaper consumer version; and a game-used or game-issued jersey is a different tier again. All three can carry a genuine signature, so the certification tells you the autograph is real while the jersey's tag and description tell you what garment you're actually buying. Read both before comparing prices between two 'signed jerseys.'

Do signed cards or signed memorabilia hold value better?

They behave differently. Signed cards — especially certified autographs sealed into the card at manufacture, like his 2019 Bowman Draft Chrome Autograph CDA-GH — trade in a deep, liquid, graded market with clear sold comps, which is covered on the autographs page. Signed memorabilia is a display market: a ball, jersey or photo is bought to be seen, supply is one-off rather than print-run driven, and pricing depends heavily on the item, the inscription and who authenticated it. Collectors chasing liquidity usually lean cards; collectors chasing a display piece lean memorabilia. Check sold comps on both before deciding.

Gunnar Henderson Signed Memorabilia: Autographed Baseballs, Jerseys, Bats & Photos

Not every Gunnar Henderson collectible is a card. Signed baseballs, jerseys, bats, photos and posters are their own market — bought to be displayed rather than slabbed, priced by the item and its certification rather than by a print run. This page covers what’s out there, how authentication actually works, and what to check before you buy, with live eBay rails for each item type.

If you’re after signed cards instead, those live on the autographs page; embedded jersey and patch pieces are on memorabilia & relic cards.

The item types

Signed baseballs — the classic entry point and the most common Henderson signed item. Where the signature sits matters: the sweet spot (the narrow panel between the seams, traditionally reserved for the marquee signature on a ball) is the most desirable placement for a single-signed ball; a side-panel signature is worth less, all else equal. The ball itself matters too — an official Major League ball is the standard; practice, minor-league and souvenir balls sit below it.
Signed jerseys — the display centrepiece. Confirm what the garment is before you compare prices: authentic (on-field spec), replica/fan, or game-used/game-issued are three different products that all show up described as “signed jersey.”
Signed bats — bigger, scarcer and usually a step up in price from balls. Same rule as jerseys: a game-model bat and a store-model bat are not the same item.
Signed photos and 8x10s — the accessible tier, and the easiest to frame. Print quality and image choice drive a surprising amount of the price.
Posters and prints — mostly unsigned display pieces, plus the occasional signed edition. Worth a rail of its own because it’s a genuinely different buying intent from the rest of this page.
Signed helmets, cleats and equipment — one-off pieces that surface irregularly; pull the “all signed items” rail to see what’s live right now.

Certification: the only thing standing between you and a fake

Autographed memorabilia is the part of the hobby with the highest counterfeit rate, because — unlike a manufacturer-certified card, where the signature is applied at the factory and sealed into the product — anyone can sign anything and call it real. Two things protect you:

MLB Authentication. Major League Baseball’s own program puts an authenticator in the room. Items get a tamper-evident hologram with a unique serial number, and you can look that number up on MLB’s authentication site to see what the item is and when it was authenticated. Because it’s witnessed, it’s the strongest provenance available for a modern signed item.

Third-party authenticators — JSA, PSA/DNA and Beckett (BAS). These issue their own numbered stickers or holograms plus a certificate, each verifiable on the authenticator’s own site. Some of their certifications are witnessed at organised signings; many are expert opinions on a signature examined after the fact. Both are widely accepted in the market, but a witnessed certification carries more weight than an opinion.

What does not protect you is a seller-issued “certificate of authenticity.” A COA is only as good as the company behind it, and an unknown company’s COA is a printed piece of paper. If the only authentication is the seller’s own, treat the item as unsigned and price it accordingly.

Always verify the serial number yourself on the issuing body’s lookup, and make sure the number in the photos matches the number on the item you’re being sent. This is the same discipline that applies to buying his graded cards — match the cert to the photos, every time.

What moves the price

Certification tier — MLB-authenticated / witnessed beats opinion-certified beats uncertified, and the gap is large.
The item underneath the signature — official ball vs souvenir ball, authentic vs replica jersey, game-model vs store-model bat.
Inscriptions — an added notation like a rookie-year or award inscription generally lifts value over a plain signature, because it takes extra time at signing and is scarcer as a result. Henderson’s 2023 AL Rookie of the Year season is the obvious inscription hook to watch for.
Placement and presentation — sweet-spot signatures on balls; clean, unfaded ink; framed vs loose.
Condition of the signature itself — see below, because this one is entirely in your hands after you buy.

Looking after a signed item

Signatures are ink on a surface, and ink fades. A few habits protect the value of anything you buy:

Keep it out of direct sunlight and away from UV. This is the single biggest killer of signed baseballs and photos — a faded autograph loses value permanently and cannot be restored.
Use a proper display case. A cube or holder for balls, a frame with UV-filtering glazing for photos and jerseys.
Don’t handle the signed surface. Skin oils degrade ink over time.
Keep the paperwork. The hologram, certificate and any signing documentation are part of the item’s value — store them together and pass them on when you sell.

Where to go next

Use the rails above to pull live eBay listings for each item type and check the sold comps before you commit. For the card side of his market: his signed cards, his flagship rookie cards, and what any Henderson card is worth. The full collecting guide and the Gunnar Henderson player hub tie the whole collection together.