#569 1953 · Gemological Institute of America (Robert Shipley, Richard Liddicoat) · Jewelry / gemology
Every diamond grade jewelers had ever used was already inflated, so GIA's new top grade started at a letter that normally means you failed
the problem
Every jeweler graded diamond color with a different self-invented scale
background
By the 1930s, American jewelers described diamond color with a chaos of self-invented, self-interested terms: some used "A," "AA" and "AAA" for their best stones, with no agreement between firms on what any of those meant; others used Roman or Arabic numerals; still others used purely descriptive phrases like "gem blue" or "blue white." A buyer had no way to compare a stone graded "AA" at one shop against one called "blue white" at another, and every grading label had been invented and applied by the same party trying to sell the stone.
Robert Shipley, a former Wichita jeweler who founded the Gemological Institute of America in 1931 after his own gemological ignorance had cost him sales, spent two decades building the professional infrastructure — a school, a research lab, a trade journal — to fix that. But even a rigorous, independently run grading scale faced an obvious risk: if GIA simply relaunched the same familiar letter system starting at "A," retailers already accustomed to inflating their own "A/AA/AAA" claims would read GIA's "A" the same way, and the new credential would inherit the exact credibility problem it existed to solve.
what everyone would do
The available path, and the one every jeweler before GIA had already taken, was some version of a letter or word scale for the best stones — A, AA, AAA, or flattering descriptive terms like "gem blue." Simply having an independent body issue that same kind of scale would not have fixed the underlying problem: buyers already associated an "A" grade with sales talk, so any new authority reusing that vocabulary risked being read as just another seller's claim, no matter how rigorously its grades were actually assigned behind the scenes.
what they saw
Shipley and Liddicoat saw that the credibility problem was not really about measurement rigor, it was about vocabulary contamination — every letter or word jewelers had already used to describe quality carried years of inflated, inconsistent claims attached to it, and reusing any of that vocabulary meant inheriting its baggage regardless of how carefully the new grades were actually assigned. Starting the scale at a letter nobody had ever used for diamonds, and one ordinarily associated with a poor grade rather than an excellent one, meant the top grade could only ever mean what GIA said it meant, because nothing else had ever claimed it first.
the move
In 1953, GIA and its incoming president Richard Liddicoat introduced the D-to-Z color grading scale, deliberately choosing "D" — a letter with no prior use in diamond grading, and one that in ordinary schoolwork signals a poor rather than a top result — as the highest, most colorless grade, specifically to sever any connection to the "A/AA/AAA" vocabulary jewelers had already devalued.
why it works
Because no jeweler's prior marketing had ever attached a meaning to "D," a buyer encountering a GIA D-graded diamond had no competing folk association to fall back on — the letter's meaning came entirely from GIA's own published definition, not from years of sales-floor inflation the way "A" or "AA" already carried. That made the scale portable across every retailer and country using it, since "D" meant the identical thing everywhere it appeared, and it let GIA's grading become something a stone's actual value could be built on rather than one more marketing claim a buyer had to discount.
the payoff
Because "D" carried no inherited marketing meaning for any retailer to exploit, a GIA "D" grade meant only what GIA had defined it to mean, and the scale became something buyers could genuinely compare across stones and stores rather than one more seller's claim to discount. GIA's D-to-Z color scale, alongside its accompanying cut, clarity and carat weight standards, became — in GIA's own account — the diamond industry's global grading standard, still in universal use worldwide more than seventy years later.
where it breaks
This only protects a new credential's meaning as long as the issuing body keeps sole, disciplined control over what the label means — the moment other parties are allowed to award or approximate a "D" grade on their own, the label starts accumulating exactly the inconsistency problem the letter was chosen to avoid. It is also a one-time trick: the unclaimed-letter maneuver only works the first time a market's vocabulary gets reset, since once the new label itself becomes trusted and valuable, a rival body copying the identical scale gains nothing beyond confusion.
what came after
The 4Cs system Shipley and Liddicoat built turned diamond grading from a seller's private claim into a portable, independently verifiable credential attached to the stone itself; JCK magazine later named Shipley its jewelry industry "Person of the Century" for the transformation. The specific choice to start the color scale at D rather than at a flattering A remains the standard illustration of how a new credential can be designed to resist the grade inflation that had discredited every scale that came before it.
references
- [1]GIA 4Cs ColorGemological Institute of America, 2024gia.edu
- [2]Robert M. Shipley Sr.: JCK's Person of the CenturyJCK Magazine, 1999jckonline.com