What Is Grade 6A Silk? An Honest Answer About Silk Grading

Grade 6A is the top grade for raw silk under China's national raw silk standard, GB/T 1797, which ranks silk 6A, 5A, 4A, 3A, 2A, A and a lowest class. Testers grade the raw silk thread itself, measuring how even, clean and neat it is. A 6A grade describes fiber quality. It says nothing about weight, weave or chemical safety.

You're comparing two silk pillowcases. Both say "6A." One costs twice as much as the other. Same grade, so same silk? Not necessarily, and the reason is worth five minutes of your time.

During chemo I looked at better silk pillowcases, but I didn't buy one, because I couldn't be sure of the quality. Grade was one of the words I kept seeing and couldn't check. So here's the plain answer about grade, what it can tell you, and how to ask a brand to back it up.

What does 6A mean on silk?

6A is a grade from a raw silk classification system. Under China's current national standard for raw silk, GB/T 1797-2008, raw silk is sorted into 6A, 5A, 4A, 3A, 2A, A and a final lowest class, from highest to lowest. 6A sits at the top.

That's consistent with how we describe it on our own site: Grade 6A is the highest commercial grade of mulberry silk. The word "mulberry" matters here. Mulberry silk comes from Bombyx mori silkworms fed on mulberry leaves. If you want the background on why mulberry silk is different from other silks, read mulberry silk vs regular silk.

Other scales exist, which is part of why the letters can be confusing. The UN Food and Agriculture Organization's silk reeling and testing manual describes the International Silk Association method, which grades 4A, 3A, 2A, A and B, and a Japanese method, which grades 5A, 4A, 3A, 2A, A, B, C and D. So "4A" on one scale and "4A" on another aren't the same rung of the ladder. When a brand says 6A, it's pointing to the Chinese scale, because that's where a 6A grade exists.

How is raw silk graded?

Grading happens early, at the raw silk stage, before the thread is ever woven into fabric. Samples from a lot of raw silk go through a set of tests in rooms held at standard temperature and humidity, and the results decide the grade.

The FAO manual lays out the logic clearly. The major tests are size deviation (how consistent the thickness of the thread is), evenness, cleanness and neatness. Cleanness and neatness are both about defects along the thread. Cleanness counts the larger ones. Neatness counts the smaller ones, such as nibs, loops, small knots and hairiness. Auxiliary tests include winding, tenacity (strength), elongation (stretch before breaking) and cohesion (how well the filaments hold together).

Here's the part most shoppers never hear. Under the method the FAO describes, the grade is set by the weakest major result, not the average. A lot that scores beautifully on four tests and poorly on one is graded by the poor one. Then shortfalls on the auxiliary tests can pull the grade down further.

A paper on raw silk testing under GB/T 1797-2008 describes the same principle for the Chinese standard: the basic grade is set by the lowest score among the primary indicators. And the standard's tolerances tighten as you climb. For fine raw silk of 12 denier and below, the allowed size deviation is 0.80 denier at 6A and 1.50 at grade A.

So a true 6A grade isn't a vibe. It's a lot of raw silk that cleared the strictest thresholds on every major test.

6A vs 5A silk: what's the difference?

5A is one grade below 6A on the same Chinese scale. Both are high grades. The difference is in the test thresholds: a 6A lot met tighter limits than a 5A lot on measures like size deviation, evenness, cleanness and neatness.

What does that mean in your hands? It's why we describe 6A as the grade with the most uniform fibers: thread that's consistent in thickness and has fewer defects along its length. I'm not going to put a number on how much smoother 6A feels than 5A, because I haven't seen a published study that measures it on finished pillowcases, and I won't invent one.

What I can describe is the day our first 25 momme samples arrived. I picked one up and knew: this is real silk. It was cool to the touch, almost refreshing. It had a beautiful weight, not heavy but substantial. It was an undeniable knowing.

But feel mixes several things at once, and here's what grade doesn't cover. A 5A silk at a heavier weight can feel more substantial than a 6A silk at a light weight. Grade and weight are separate dials.

What does silk grade not tell you?

Grade describes the raw silk thread. It doesn't describe:

• Weight. That's momme, a separate measure of how much silk is in the fabric. 6A silk can be woven light or heavy, so the grade alone won't tell you which. Why momme weight matters explains the scale.
• Weave. Charmeuse, habotai and other weaves change the surface and drape. Grade doesn't tell you which one you're getting.
• Chemical safety. Grade doesn't test dyes or finishes. That's what OEKO-TEX Standard 100 testing is for.
• Organic fiber origin. Grade doesn't audit how the silk was produced. That's GOTS.

Here's how the main specs compare, and which ones you can actually check from your couch.

Can you verify a 6A claim?

This is the honest nuance. 6A is a real grade on a real national standard, and it's meaningful. But it lives in lab reports and supplier paperwork at the raw silk stage, long before a pillowcase is sewn.

GOTS and OEKO-TEX are built for checking. OEKO-TEX's Label Check lets anyone enter a certificate number and confirm whether it's valid; here's how to run an OEKO-TEX Label Check. GOTS asks consumers to check its certified suppliers database, and a complete GOTS label names the certifier and a license number; see how to verify a GOTS certificate. I haven't found any equivalent public database where you can type in a pillowcase and see its silk grade.

So for most shoppers, 6A is a claim you have to trust. That doesn't make it false. It means grade works best paired with things you can check yourself. That's exactly why Performance Luxury Silk™ puts grade next to two certificates with public numbers. What is Performance Luxury Silk? walks through all four parts.

How do you ask a brand about silk grade?

A brand that says 6A should be comfortable answering questions about it. Here's what to ask, in order:

1. "Which grading standard is your 6A from?" The answer should be the Chinese raw silk standard. If they can't say, that's a flag.
2. "Can you share a test report or supplier spec sheet for the raw silk?" A summary, or a page with commercial details blacked out, is a fair answer.
3. "Is the whole product 6A, or only part of it?" Ask whether every silk panel uses the same grade.
4. "What momme is it?" A grade with no weight is half a spec.
5. "What are your GOTS and OEKO-TEX numbers?" These are the claims you can look up tonight.

If the answers are vague, weigh the claim accordingly. For the full checklist on judging a pillowcase, see what to look for in a high-quality silk pillowcase.

Are two 6A silk pillowcases the same?

Back to those two pillowcases. If both claims are true, the same grade tells you the raw thread cleared the same top thresholds. It doesn't tell you the momme, the weave, or whether the finished piece was tested for harmful substances. The price gap could live in any of those other dials. The letters start the conversation. The numbers you can look up finish it.

What grade is Wink Silk?

Every Wink piece is Grade 6A, 100% mulberry silk at 25 momme. That includes the Douceur™ pillowcase ($185, single layer), the double-layer Douceur Doublure™ ($245, 330 hand-numbered founding pieces, never restocked), the Voile™ contoured eye mask ($148) and the Soie™ scrunchies ($28 to $42). The pillowcases are charmeuse and queen only for now.

We evaluated 15 silk makers before choosing our silk house. I chose 25 momme because I wanted heavier silk that's smoother on skin and hair and lasts through more washings. We're a family of seven, so that's a lot of laundry.

Grade is one of the four parts of our Performance Luxury Silk standard, which is our own standard, not an industry certification. The two parts you can verify yourself: every piece is crafted by a GOTS & OEKO-TEX certified silk house, GOTS license 00284622 (certified by ECOCERT), with OEKO-TEX Standard 100 certificate 22.HCN.30712 for pillowcases and 19.HCN.84688 for eye masks and scrunchies, both Product Class I. Wink Silk is pursuing its own GOTS Trader and OEKO-TEX certifications.

When you're ready, Wink Privé opens November 2, three days before everyone else, and the public launch is November 5, 2026. Returns are free for 30 days, US shipping is free, and you can cancel for a full refund any time before your order ships. Ship date confirmed by email after purchase. Join Wink Privé to hold a founding number.

Wink. The brand that shows you the certificates.

Sleep beautifully.

Sources

• Related standards for GB 1797, including GB/T 1797-2008 Raw silk: ChineseStandard.net
• Silk Reeling and Testing Manual, Chapter 11: Raw Silk Testing: FAO
• Correlation Between Indicators of the Electronic Testing and the Current Test for Raw Silk: Atlantis Press
• OEKO-TEX Label Check
• GOTS consumer security advice (PDF)
• Wink Silk: Silk Glossary, FAQ, Douceur, Douceur Doublure, Certifications

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