G23 Implant Grade Titanium, Grade by Grade

What G23 actually designates

G23 is shorthand for Grade 23 titanium, which is the trade name for the alloy Ti-6Al-4V ELI, which is the material specified by ASTM F136 - a standard whose full title is “Wrought Titanium-6Aluminum-4Vanadium ELI Alloy for Surgical Implant Applications.” All four of those names describe one material. A listing that says G23, one that says Grade 23, one that says F136 and one that says Ti-6Al-4V ELI are making the same claim.

Owning it is as undemanding as the specification suggests - nothing to tarnish, no coating to protect - and the one real exception, anodized color, is covered in how to clean titanium jewelry. The hinged small-hoop format this alloy is most often bought in is ranked in best huggie earrings.

The composition is roughly 90% titanium, 5.5-6.75% aluminum and 3.5-4.5% vanadium, with the balance tightly controlled impurities. The ELI part is the point: extra low interstitial means the standard caps oxygen, nitrogen, carbon and iron more strictly than the ordinary version of the same alloy does. That is a metallurgical distinction made for implant fatigue performance, and for an earring post it is close to irrelevant.

What is not irrelevant is the word standard. G23 points at a document with a number, published by a standards body, that says what the metal may and may not contain. That makes the claim falsifiable. Almost nothing else in the hypoallergenic-earring aisle is - which is the argument made at length on what ‘hypoallergenic’ actually means.

Every designation you will see, and what each one names

Titanium is sold in jewelry under at least eight labels. They are not interchangeable, and three of them name nothing at all.

G23 against G5: the same alloy, two documents

This is the comparison that confuses people most, because the answer is undramatic. Grade 5 and Grade 23 are the same alloy formula - Ti-6Al-4V. Grade 23 is the ELI variant, held to tighter impurity limits. Both are nickel-free. Both resist corrosion the same way, because corrosion resistance comes from the titanium oxide layer that forms on any titanium surface, and that layer does not care about interstitial oxygen content.

The Association of Professional Piercers names four titanium specifications as appropriate for initial piercings: ASTM F136, ASTM F67, ASTM F1295 and ISO 5832-3. That last one is Grade 5. So a piece of Grade 5 titanium certified to ISO 5832-3 is, by the APP’s own list, acceptable in an unhealed piercing - and anyone telling you G5 is dangerous is overstating it.

The practical catch is upstream of the metallurgy. “G5” on an Amazon listing is a grade name, not a certification, and at this price point nothing on the page tells you whether the stock met ISO 5832-3 or merely matched the formula. G23 listings tend to cite F136 explicitly because the phrase “implant grade” is the selling point. You are not choosing a better alloy when you choose G23 over G5. You are choosing the listing more likely to name its standard - and that is a real thing to choose on.

G23 against commercially pure titanium

Commercially pure titanium - Grades 1 through 4 under ASTM F67 - has no aluminum and no vanadium in it. The four grades differ mainly in oxygen content, which is why Grade 1 is the softest and most formable and Grade 4 the strongest. Pure titanium is weaker than Ti-6Al-4V: Grade 1 runs around 240 MPa tensile strength against roughly 860 MPa minimum for F136.

For a hip stem that difference decides the design. For an earring post it decides almost nothing, because an earring post is never loaded. Where CP titanium has a genuine edge is for the small number of people reacting to something in the alloy rather than to nickel - there is no aluminum and no vanadium present to react to. If you have worked through G23 and still have symptoms, CP titanium or niobium is the next thing to try, and the sensitive skin guide covers what else to rule out before concluding it is the metal.

How to check whether a listing's G23 claim is real

You cannot verify an alloy from a photograph, and nobody is going to send you a mill certificate for a $10 pair of studs. What you can do is read the listing for the tells that separate a seller who knows their material from one who copied a keyword.

• A standard number appears somewhere. F136, ASTM F136, or ISO 5832-3. The phrase “implant grade” on its own is marketing; the number is a claim.
• The gauge is stated. 20G, 18G, 16G. A seller who knows piercing jewelry states the gauge, because it is the spec that decides whether the earring physically fits.
• The grade covers the whole piece, not just the post. A titanium post in a plated brass setting is a plated brass earring touching your lobe. If a stone is set, the listing should say what the setting is.
• Nothing says “titanium steel” or “titanium plated.” Both of those phrases describe a steel or base-metal item. Neither is titanium in any sense that affects your skin.
• The price is plausible. Titanium earrings are cheap - genuinely, boringly cheap. Low price is not the red flag here. A low price plus no gauge, no standard and the word “hypoallergenic” doing all the work is the flag. More of those patterns are cataloged in how to read a jewelry listing.

Gauge and threading: the two specs that decide whether it fits

Grade decides whether the metal is safe. Gauge and threading decide whether the earring goes in at all, and they are the two specs most often missing from a listing that is otherwise shouting about its alloy.

Gauge is post thickness, and the scale runs backwards - a higher number is a thinner post. Standard pierced lobes are usually 18G or 20G; 16G is common in cartilage and in piercings done at a studio rather than with a gun. An 18G post will not go through a snug 20G hole without forcing it, and forcing it is how a healed piercing gets irritated for a week or two. If you do not know your gauge, 20G is the safer purchase, because a thinner post always fits a wider hole.

Threading is how the back attaches, and there are three systems.Push-through is the ordinary stud with a butterfly back - no thread, easiest to use, least secure. Internally threaded means the post has a threaded hole and the back screws into it, so nothing sharp passes through the piercing; this is what piercers specify. Externally threaded means the thread is on the post, which drags across the piercing channel on the way in - fine in a healed lobe, poor practice in anything fresh. Threadless uses a bent pin held by tension, which is the most comfortable and the easiest to lose.

A listing that names its grade, its gauge and its threading system is a listing written by someone who sells to piercers. That combination is a better quality signal than any adjective on the page, and it is worth more than a star rating. The flat-back version of this decision is covered in best flat back earrings, and the timing caution for anything still healing is in earrings for new piercings.

G23 against 316L surgical steel

This is the comparison that matters for anyone who already reacts to earrings, because 316L is what most “hypoallergenic” earrings actually are. The relevant fact is in the title of the steel standard itself: ASTM F138 covers “Wrought 18Chromium-14Nickel-2.5Molybdenum Stainless Steel.” Nickel is named in the specification. Implant steel is implant-safe because the nickel is locked in the alloy matrix and releases very slowly, not because it is absent.

For most people that is fine, and steel earrings are a sensible purchase. For someone with a diagnosed nickel allergy, “releases slowly” and “contains none” are different promises. G23 is the one that contains none. That is the entire reason this grade is worth knowing about, and it is why best metal for sensitive ears lands where it does. The fuller argument about the steel phrase is on what is surgical steel.

Where the grade stops mattering

Grade is a biocompatibility question, so it earns its weight exactly where metal sits against broken or healing skin: a fresh piercing, a cartilage piercing, an earring you sleep in and never remove. In those cases buy the grade-stated piece and stop thinking about it.

It matters much less for an earring you wear for an evening and take out, and it matters not at all for a necklace or a bracelet, where the metal sits on intact skin. If your ears are fine with sterling and steel, G23 buys you nothing except a cooler gray color than silver and a piece that will never tarnish. Titanium does not tarnish because it has no silver to sulfide and no copper to oxidize, which is also why it needs no cleaning routine at all - unlike nearly everything in how to clean silver jewelry.

What G23 looks like, honestly

Titanium is gray. It is a flatter, cooler, slightly darker gray than sterling silver, and it does not take the same mirror polish. Next to a silver hoop the difference is visible; next to a gold stack it reads as the wrong metal entirely. Anodized titanium - the rainbow and gold-tone finishes sold in piercing shops - gets its color from a surface oxide layer grown electrically, not from a coating, so it does not flake off, but it does fade with abrasion over years.

If what you want is gold-colored and your ears are not reactive, titanium is the wrong purchase and gold-filled is the right one at a similar price. The difference between gold-filled and the things sold beside it is set out in gold types explained, and the dipped-and-washed vocabulary is unpicked in gold dipped vs gold plated.