Open Access Explained: Gold, Green, Diamond & Hybrid — A Guide for African Researchers

What “open access” actually means

Open access (OA) means research that is free to read online, with no subscription and no paywall between the reader and the work. The founding definition comes from the Budapest Open Access Initiative of 2002, which described OA as literature made “freely available on the public internet, permitting any user to read, download, copy, distribute, print, search, or link to the full texts.” That is the goal every model below is trying to reach — they simply take different roads to it, and split the cost differently along the way.

Two distinctions unlock everything that follows. The first is about rights. Scholars separate gratis OA — free to read, but with normal copyright still restricting reuse — from libre OA — free to read and carrying an open licence (usually a Creative Commons licence such as CC BY) that also permits reuse, translation and text-mining. Libre is the fuller form of open access.

The second distinction is about where the open copy lives, and it gives us the two original “roads” named by cognitive scientist Stevan Harnad: the gold road, where the journal itself publishes the article openly, and the green road, where the author deposits a copy in a repository. Everything marketers now call “gold, green, diamond, hybrid” is a refinement of those two ideas plus one question: who pays, and how much?

The four models at a glance

Before the detail, here is the whole landscape on one screen. Read it as: where is the open copy, who pays, and what does it cost me as the author?

Gold, green, diamond & hybrid — one by one

Gold open access

In the gold model, the journal makes the final, peer-reviewed, published version of your article free to everyone, immediately, on its own website — normally under a Creative Commons licence. This is the version of record: the polished, typeset, citable article. Fully open-access journals are indexed and vetted in the Directory of Open Access Journals (DOAJ), which lists over 20,000 journals from more than 130 countries and is the standard whitelist for checking that a gold journal is genuine. The catch some researchers hit is cost: many well-known gold journals fund themselves by charging the author an APC.

Green open access

Green OA is self-archiving. You publish in whatever journal you like — including a subscription one — and separately deposit a copy of your work in an open repository: your university’s institutional repository, or a subject repository or preprint server. The version you are usually allowed to post is the accepted manuscript (the peer-reviewed text, before the publisher’s typesetting), and publishers often impose an embargo — a delay of 6 to 24 months before the repository copy can go live. Green costs the author nothing, and every publisher’s specific rules are searchable in Sherpa Romeo, the standard database of journal self-archiving policies.

Diamond (or platinum) open access

Diamond OA is gold’s more generous sibling: the journal is free to read and free to publish — no APC at all. The running costs are covered by a university, a learned society, a library consortium or a government, rather than by the author. This model quietly dominates the real world of open access: the 2021 OA Diamond Journals Study, commissioned by cOAlition S and Science Europe, estimated 17,000–29,000 such journals worldwide, and they are especially common across Africa, Latin America and Asia. For a Nigerian researcher without grant money for fees, diamond is often the ideal home. We cover it in depth in our dedicated guide to diamond open access.

Hybrid open access

A hybrid journal is a subscription journal that also offers, for a fee, to make your individual article open while the rest of the issue stays paywalled. It is the most contested model, because the publisher can be paid twice for the same journal — once through library subscriptions and again through your APC. Critics call this “double dipping.” Hybrid APCs are typically the highest of any route, and the major open-access funder alliance Plan S will not, as a rule, pay for standalone hybrid publishing. For a self-funding African author, hybrid is the route to approach with the most caution.

Bronze, and what is not open access

You will also meet bronze OA: an article that is free to read on the publisher’s site but carries no open licence. A large 2018 study in PeerJ found bronze was actually the most common form of free-to-read scholarship online. The problem is that “free today” is not “open”: with no licence, the publisher can move the article behind a paywall whenever it chooses, and your right to reuse or redistribute it is unclear. Treat bronze as a courtesy, not a guarantee.

What it really costs — APCs & waivers

The Article Processing Charge (APC) is the fee some journals charge to publish your article openly. Its range is enormous: from zero at every diamond and green route, through a few hundred dollars at many mid-tier gold journals, up to headline figures like US$12,690 to publish open access in Nature. At the top end, a single APC can exceed a Nigerian academic’s monthly salary many times over — which is exactly why understanding the free routes matters so much here.

But the headline hides the good news, and it is worth stating plainly: most open-access journals charge no fee at all. Analyses of DOAJ consistently find that roughly two-thirds of its indexed journals levy no APC. The “open access means paying” assumption that puts so many African researchers off is simply not true of the majority of the field.

Choosing your route as a Nigerian researcher

Put the theory to work. For most researchers publishing from Nigeria without a dedicated APC budget, the decision runs in this order.

Identifiers, discovery & how FRELIP helps

Choosing an open-access model is one half of making your work count; making it findable and correctly credited is the other. That is where persistent identifiers come in. Whichever route you choose, pair your paper with a DOI so it stays citable, and link it to your ORCID iD so the credit lands with you. Open access decides who can read your work; identifiers decide who can find and attribute it.

The takeaway is simple. Open access is a family, not a single door. Reach first for diamond, keep green in your back pocket for everything else, treat gold’s fees as negotiable through waivers, and be wary of hybrid. Do that, and your research reaches its readers — without a fee standing between you and the people your work is for.

FRELIP fact-check report

Every claim here was checked against primary sources: the Budapest Open Access Initiative, DOAJ, UNESCO, the OA Diamond Journals Study and the published OA literature. We separate what those sources confirm from what is reported but not fully settled.

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