ISO 3632 Saffron Grades Explained (Category I, II, III)
The laboratory standard
ISO 3632 Saffron Grades, Explained
Almost every saffron label in America says premium. Only a laboratory number can prove it. Here is how the international grading standard actually works — and how to read it like a buyer who cannot be fooled.
ISO 3632 is the international standard for saffron — the one framework under which a neutral laboratory, rather than a marketing department, decides what a jar of red threads is worth. A sample is dissolved, passed through a spectrophotometer, and measured for the three compounds that make saffron saffron: crocin for color, picrocrocin for taste, and safranal for aroma. The results place the lot into Category I, II, or III. There is no Category "Premium," no Category "Grade A+," and no category awarded for a handsome label.
That last point matters more than most shoppers realize. Words like finest, select, and gourmet are legally decorative — any importer can print them. Even honest-sounding grade names get borrowed: bottles labeled "Super Negin" sometimes hold broken, faded threads that would struggle to reach Category II under test. When we audited the best-selling saffron brands in the USA, the single sharpest dividing line was not price or packaging — it was whether the seller published a recent ISO 3632 lab report at all. Most do not.
This page is the reference we wish we'd had when our family started trading saffron out of Herat in 1996: what each measurement means, where the category thresholds actually sit, how the thread-cut ladder (Super Negin down to Dasteh) relates to — and differs from — the lab categories, and how to read a certificate in thirty seconds. If you want the broader curriculum, our Learn hub maps every guide in the series.
What the lab measures
Three compounds, three numbers
Under ISO 3632, a ground sample is dissolved in water and read by spectrophotometer — for crocin, as absorbance at 440 nm expressed as E1%1cm, the standard's shorthand for "how strongly a 1% solution absorbs light." Each compound peaks at its own wavelength, which is why one test yields three independent scores. The numbers below are our current lot's results from the Herat Directorate of Agriculture laboratory.
Crocin · Color · 440 nm
296.5OURS
The carotenoid that turns a pot of rice gold. The headline number: it tracks how much coloring power each thread carries, and Category I demands at least 200 of it.
Picrocrocin · Taste · 257 nm
114.2OURS
The glycoside behind saffron's pleasantly bitter, earthy backbone — the depth that separates real saffron flavor from mere yellow color.
Safranal · Aroma · 330 nm
32.7OURS
The volatile oil that smells of honey and fresh hay. Being volatile, it fades first — one reason saffron is best used within about two years of harvest.
Crocin leads every certificate because it is the hardest to fake and the easiest to verify: dye can imitate color in a photograph, but not absorbance at a specific wavelength in solution. It is also the number with the most practical consequence in your kitchen — more on that below.
The category ledger
Where the lines are drawn
ISO 3632 sorts saffron into three categories by its crocin coloring strength. The gap between them is not academic: a Category I thread can carry roughly two-thirds more coloring power than a thread scraping into Category III, which means fewer threads per dish and a lower real cost per serving — whatever the per-gram price tag says.
Crocin coloring strengththis lot, tested in Herat
| Category | Crocin minimum | What it means | Where you find it |
|---|---|---|---|
| Category I | ≥ 200 | The top band. Deep, fast color release; full aroma. The grade serious kitchens specify. | Specialist growers who publish lab reports. Our lot: 296.5. |
| Category II | ≥ 170 | Respectable mid-grade; needs a noticeably larger pinch for the same color. | Better supermarket jars and restaurant-supply stock. |
| Category III | ≥ 120 | The floor of the standard. Weak color, muted aroma — often older or style-heavy stock. | Bargain bins, bulk jars with no harvest date. |
Two honest caveats. First, a category describes a tested lot, not a brand: last year's certificate says nothing about this year's jar, which is why the harvest date printed next to the number matters. Second, the standard has a floor — saffron testing below Category III should not be sold as saffron at all, yet plenty of it is. If a seller quotes no number and no date, our saffron price guide shows why suspiciously cheap threads almost always resolve to exactly that gap.
The other grading language
The thread-cut ladder: Super Negin to Dasteh
Alongside the lab categories runs an older, physical grading language — Persian and Afghan trade terms describing which part of the stigma you're buying and how it was cut. The two systems answer different questions. ISO 3632 asks "how potent is this saffron?"; the cut ladder asks "how much of what you paid for is actually red stigma?" The best saffron scores at the top of both.
Super Negin
Long, unbroken, uniformly deep-crimson threads with the yellow style cut entirely away, trimmed to a blunt flat tip. The most labor per gram and the highest concentration of crocin-bearing tissue. This is the cut we bottle.
Negin
All-red and largely intact, but shorter and less uniform than Super Negin — excellent saffron, one notch down in visual and sorting rigor.
Sargol
"Top of the flower": red stigma tips only, machine- or hand-cut. Potent but fragmentary — more broken threads and powder in the jar.
Pushal
Red threads still attached to a length of pale yellow style. You're paying thread prices for a portion of flavorless stem — it pads weight, not color.
Bunch (Dasteh)
Whole stigmas and styles tied in a bundle, red fading to white. Traditional, picturesque, and the weakest coloring strength per gram of any cut.
The trap to avoid: "Super Negin" on a label is a claim about cut, not a lab result. A jar can hold genuine Super Negin from an old harvest whose safranal has faded, or — worse — dyed lower-grade threads posing as it. The reverse is also true: a Category I certificate can sit on broken Sargol. Cut tells you what you see; category tells you what it will do in the pot. Insist on both, and if the threads themselves look doubtful, run them through our five at-home authenticity tests before you cook.
Thirty-second literacy
How to read a saffron certificate
- Who tested it. A named, independent laboratory — a government agriculture directorate or accredited food lab. "Tested in our own facility" is not a certificate.
- When. The test date should match the current harvest. Crocin is fairly stable, but safranal decays; a three-year-old report describes saffron that no longer exists.
- The three values, stated numerically. Not "Category I" alone — the actual crocin, picrocrocin, and safranal readings. A seller confident in 296.5 prints 296.5.
- The method. A reference to ISO 3632 and spectrophotometric analysis (absorbance at 440 nm for crocin) shows the lab followed the standard rather than a house scale.
- Purity remarks. The report should note whether artificial colorants were detected. Ours states plainly: none.
Why any of this matters
What a high grade means in the kitchen
Here is the entire economics of saffron grades in one sentence: the higher the crocin, the fewer threads each dish needs. A standard pinch is 8–15 threads. At 296.5 crocin — nearly half again the Category I minimum — that pinch blooms into a deep amber liquid in 10–15 minutes of warm (never boiling) water and carries a full pot of rice. Weaker saffron forces you to double the pinch and still settle for paler results, which is how a "cheap" jar quietly becomes the expensive one per serving.
The arithmetic is friendly at this strength. One gram is roughly 250 threads — about 15–20 family-sized dishes — and behind that gram stand some 150 hand-picked crocus flowers. Spread across a risotto alla Milanese or an Afghan qabuli palaw, Category I saffron at $15 per gram costs well under a dollar a serving. Our guide to using saffron — dosage, blooming, and ratios turns those numbers into exact per-dish measures.
One last kitchen note the certificate hints at: safranal, the aroma compound, is volatile. Even perfectly stored saffron fades meaningfully after about two years, so buy quantities you'll actually cook through and keep the bottle sealed, cool, and dark — our storage guide covers the details. A harvest date on the label is not a nicety; it's the expiry logic of the aroma itself.
Questions, answered
ISO 3632, in brief
What is ISO 3632?
ISO 3632 is the international laboratory standard for grading saffron. An independent lab measures three compounds by spectrophotometer — crocin (color), picrocrocin (taste), and safranal (aroma) — and assigns the lot to Category I, II, or III based on its crocin coloring strength.
What is Category I saffron?
Category I is the top ISO 3632 band, requiring a crocin coloring strength of at least 200. Category II requires at least 170 and Category III at least 120. Higher crocin means more coloring power per thread, so you use less per dish. Our current lot tested 296.5.
Is Super Negin the same as Category I?
No — and this trips up most buyers. Super Negin describes the physical cut: long, unbroken, all-red threads with the yellow style removed. Category I is a laboratory measurement of coloring strength. Saffron can be one without the other; the best saffron is both, verified by a dated lab report.
What crocin number should I look for?
Anything at 200 or above is genuine Category I. From there, higher is measurably better: more color and aroma per gram, fewer threads per dish. Treat a seller who states no number at all as unwilling to be tested.
Does a higher ISO category actually taste better?
It means more of the compounds responsible for color, taste, and aroma in every gram. Practically, you need fewer threads for a fuller result, which usually makes a strong Category I saffron cheaper per serving than a weak bargain jar — despite the higher price per gram.
Where can I see Raihan's own lab results?
Our current lot tested crocin 296.5, picrocrocin 114.2, and safranal 32.7 at the Herat Directorate of Agriculture laboratory — ISO 3632 Category I, with no artificial colorants detected. The full certificate is published on our verification page.
Tested, dated, bottled
Taste what 296.5 means
3 g bottle · $45 · the first bottle that ships free
Shop the 3 g bottle →Super Negin cut, Category I tested — hand-separated in Herat, Afghanistan; bottled by the Qutubzad family, in the trade since 1996.
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