Gem rate is the percentage of submissions that a grading company returns at its gem-mint top grade. For PSA, gem rate is the share of cards graded PSA 10 out of all PSA submissions of that card. PSA 10 is the gem-mint grade — the highest a PSA-graded card can receive.

Where do I look up gem rate for a specific card?

Public population reports list cumulative grades per card by grader. PSA's Population Report (psacard.com/pop) is free and authoritative for PSA. CGC and BGS publish their own. The gem rate calculation is: (PSA 10 count) / (total graded count). For the most accurate version, factor out cards that were resubmitted-for-upgrade — those skew the rate upward.

Is a 10% gem rate good?

It depends on the card. For modern Pokémon ex/V/VMAX cards, 10% PSA 10 is below average — clean modern cards often hit 20-40%. For vintage Pokémon WOTC holos, 10% is exceptional — most WOTC holos clock in at 1-5% due to centering and edge wear. Always benchmark against comparable cards in the same era.

How does gem rate change the grading economics?

The optimizer computes expected value as: (P(grade 10) × comp_10) + (P(grade 9) × comp_9) + (P(below 9) × comp_below_9). If gem rate is 5% and PSA 10 comp is $1,000 while PSA 9 is $100 and below-9 is $40, EV is (0.05 × $1,000) + (0.7 × $100) + (0.25 × $40) = $50 + $70 + $10 = $130. The PSA 10 contribution is small relative to PSA 9 even though the PSA 10 price is 10× higher.

What's the difference between gem rate and population growth?

Gem rate is a stock — what fraction of cards graded so far are at the top grade. Population growth is a flow — how many cards are being graded per month. A card with high gem rate AND high population growth has falling slab premiums (PSA 10s are accumulating faster than buyers absorb them). A card with low gem rate AND high population growth has stable premiums. Both metrics matter; the platform's roadmap surfaces both once the GemRate partnership lands.

What Is Gem Rate (And Why It Matters)

Every grading-flip decision comes down to one input: what's the probability my card grades a 10? That probability is the gem rate. Get it wrong by 20 percentage points and a "profitable" grading flip becomes a $50 loss after fees. Get it right and you can rank-order which of the 50,000+ cards in your collection are actually worth sending in.

What gem rate means

Formally:

Gem rate = (count of grade-10 returns) ÷ (total submissions graded). Per-grader, per-card, computed from cumulative pop-report data.

PSA 10 is the gem-mint grade for PSA-graded cards. BGS uses 10 (with the special Pristine 10 "Black Label" requiring all four subgrades at 10.0). CGC uses 10 with a separate Pristine 10. Each grader's gem rate is its own number — they don't interchange.

The gem rate matters because the slab premium — the markup of a graded card over a raw card — is overwhelmingly concentrated at the top grade. A PSA 10 typically sells for 5-50× the raw market price; a PSA 9 of the same card sells for 1.2-3× raw. The decision to grade a card is really a decision to bet at gem-rate odds on hitting the 10.

Where to look it up

Authoritative sources:

PSA Population Report — psacard.com/pop. Free lookup by card. Lists cumulative counts at every grade. Most comprehensive for Pokémon and modern sports.
CGC Trading Cards Census — cgccards.com. Public.
BGS Population — beckett.com (BGS). Public, narrower history than PSA.
GemRate — commercial aggregator across all four major graders. Cardboard Assets is in active onboarding with GemRate — once that integration completes, the gem rate is computed automatically per card across all graders simultaneously. See the methodology page.

Until GemRate lands, the platform's gem-rate values for cards in optimizer detail are hand-verified against PSA Pop Report. The grade_probs_source field on every optimizer row is either manual_verified (hand-confirmed), gemrate (partner data), or manual_seed (BETA — labeled as verifying). The optimizer page surfaces this provenance on every card.

Typical ranges by era

Gem rates vary wildly by era and rarity. Some benchmarks:

Era	Typical PSA 10 gem rate	Why
WOTC vintage (Base–Skyridge)	1–5%	27-year-old cards, era-typical centering issues, edge wear from handling
Pokémon EX series (2003–2007)	3–10%	Improved cardboard but still pre-modern QC
Pokémon Sun & Moon / Sword & Shield	10–25%	Modern QC, decent centering on most prints
Pokémon Scarlet & Violet (ex / SIR)	15–35%	Tightest modern QC; SIR alternate art often clean
MTG vintage (Alpha–Tempest)	2–8%	30+ year-old cards; centering tolerances were lax
MTG modern (post-Modern Horizons)	10–30%	Print QC modernized; foil curl is a leading reason for 9s

These are population ranges — meaning the cumulative submissions skew toward cards graders thought would do well. A random raw card from the same era likely scores below the population gem rate. Account for selection bias when estimating your specific copy's odds.

How it changes the math

Take a worked example. Suppose:

Raw market price: $50
PSA 10 comp price: $1,000
PSA 9 comp price: $100
PSA <9 comp price: $30
PSA grading fee: $30
Return shipping: $15
eBay fee on sale price: 13.25% + $0.30

Expected value (EV) before fees, given gem rate g, 9-rate p9, sub-9 rate (1 − g − p9):

EV = g × $1,000 + p9 × $100 + (1 − g − p9) × $30

At 5% gem rate and 70% 9-rate (typical vintage WOTC):

EV = 0.05 × $1,000 + 0.70 × $100 + 0.25 × $30 = $50 + $70 + $7.50 = $127.50

Net after fees: EV − raw − grading − shipping − eBay fee

$127.50 − $50 − $30 − $15 − ($127.50 × 0.1325 + $0.30) = $127.50 − $95.30 = −$13.85

Verdict: SKIP. The 5% gem rate isn't high enough to overcome the fees at this price-stack.

Now bump gem rate to 20% (typical modern Pokémon ex) and rerun:

EV = 0.20 × $1,000 + 0.65 × $100 + 0.15 × $30 = $200 + $65 + $4.50 = $269.50

Net = $269.50 − $50 − $30 − $15 − ($269.50 × 0.1325 + $0.30) = $269.50 − $130.99 = +$138.51

Verdict: GRADE. The 15-percentage-point gem-rate bump turned a $14 loss into a $139 win. That's the leverage of gem rate.

Why the platform exposes the math

Every card on cardboardassets.com surfaces these inputs explicitly — gem-rate source, comp source, fee assumptions. Override any of them with your own number and the verdict re-computes. The math is transparent because it's the only way to know when to not trust the platform's default.

Common pitfalls

Using cumulative pop-report numbers without resub correction. A card with 60% PSA 10 rate might actually have 25% true rate — the other 35% is the same cards graded multiple times until they hit. Some collectors crack-and-resub until they get the 10. Use eBay-listed-but-unsold PSA 9 counts as a sanity check.
Confusing "PSA 10" with "BGS 10." Different graders, different grading standards, different premium curves. A BGS 10 isn't worth what a PSA 10 is.
Ignoring centering specifically. Most cards that hit PSA 9 instead of 10 lose the grade on centering. If your copy looks visually 60/40 or worse, the gem-rate doesn't apply to you — your odds are much lower.
Treating SIR / VMAX / chase cards' gem rates as the set baseline. Modern Pokémon's headline 25% gem rate is for chase cards everyone submits clean copies of. Common holos from the same set might be 10%.

Frequently asked questions

What is gem rate?: Gem rate is the percentage of submissions that a grading company returns at its gem-mint top grade. For PSA, gem rate is the share of cards graded PSA 10 out of all PSA submissions of that card. PSA 10 is the gem-mint grade — the highest a PSA-graded card can receive.
Where do I look up gem rate for a specific card?: Public population reports list cumulative grades per card by grader. PSA's Population Report (psacard.com/pop) is free and authoritative for PSA. CGC and BGS publish their own. The gem rate calculation is: (PSA 10 count) / (total graded count). For the most accurate version, factor out cards that were resubmitted-for-upgrade — those skew the rate upward.
Is a 10% gem rate good?: It depends on the card. For modern Pokémon ex/V/VMAX cards, 10% PSA 10 is below average — clean modern cards often hit 20-40%. For vintage Pokémon WOTC holos, 10% is exceptional — most WOTC holos clock in at 1-5% due to centering and edge wear. Always benchmark against comparable cards in the same era.
How does gem rate change the grading economics?: The optimizer computes expected value as: (P(grade 10) × comp_10) + (P(grade 9) × comp_9) + (P(below 9) × comp_below_9). If gem rate is 5% and PSA 10 comp is $1,000 while PSA 9 is $100 and below-9 is $40, EV is (0.05 × $1,000) + (0.7 × $100) + (0.25 × $40) = $50 + $70 + $10 = $130. The PSA 10 contribution is small relative to PSA 9 even though the PSA 10 price is 10× higher.
What's the difference between gem rate and population growth?: Gem rate is a stock — what fraction of cards graded so far are at the top grade. Population growth is a flow — how many cards are being graded per month. A card with high gem rate AND high population growth has falling slab premiums (PSA 10s are accumulating faster than buyers absorb them). A card with low gem rate AND high population growth has stable premiums. Both metrics matter; the platform's roadmap surfaces both once the GemRate partnership lands.