RAPI restates all five daily points read a day earlier
The one-carat series read on 21 September and again on 22 September differs at every overlapping date, by between 12 and 27 cents. The level is barely changed; the dating of a quote is not.
By The Diamond Desk
What changed
The series moved. Every one of the five daily points published between 16 and 20 September has moved. The series read on 22 September differs from the same page read on 21 September.
What it means
- If you quote off RAPI: Date the read, not only the point. Two people quoting the same day can hold different numbers.
- If you settle contracts on it: The moves are under three-tenths of a dollar, immaterial at one carat.
- What this is not: An error. A revised series is ordinary; an undated quote is the risk.
Key figures
| Points that moved16–20 September | 5 of 5 |
|---|---|
| Largest restatement | $0.27 |
| Largest, as a share | 0.007% |
| Newest point, 21 Sep | $3,918.53 |
Source: RapNet Diamond Index, 1.00ct, D–H / IF–VS2 · series read 22 September 2026, compared with Carat Capital's read of the same page on 21 September
Every point moved
Five for five. Each of the five points dated 16 to 20 September reads differently on the two mornings. Three fell by about a quarter of a dollar; two rose by twelve cents.
The shifts cluster. The moves take two values, not five: minus 26 or 27 cents, or plus 12 cents. Random transcription noise would not group that tightly.
| Point dated | Read 21 September | Read 22 September | Move |
|---|---|---|---|
| 16 September | $3,912.17 | $3,911.91 | −$0.26 |
| 17 September | $3,911.01 | $3,910.74 | −$0.27 |
| 18 September | $3,916.46 | $3,916.19 | −$0.27 |
| 19 September | $3,914.90 | $3,915.02 | +$0.12 |
| 20 September | $3,916.07 | $3,916.19 | +$0.12 |
| 21 September | not yet published | $3,918.53 | new point |
Notes on this table
Both columns are in-house reads. the right column was parsed from the page's own embedded daily series on 22 September 2026. The left column is Carat Capital's standards desk reading of the same URL on 21 September, recorded in its dated file before this article was written. It is an internal record, not a third-party publication, and is labelled as one.
The arithmetic. 0.27 ÷ 3,916.46 = 0.0069%, printed as 0.007%.
No restatement policy is published. the index page carries no note explaining when or why a published point is revised, and no mechanism is being claimed here.
The level barely changed
Small in dollars. The largest single restatement is 27 cents against a level near $3,916, or 0.007%. The division is 0.27 over 3,916.46.
A new point arrived. The series also added a point for 21 September at $3,918.53, above every reading in the five days before it.
A quote now needs two dates
Two dates, one number. A RAPI figure needs the date it was read as well as the date of the point. Without both, two correct quotes of the same point can disagree.
What to watch
- 23 September 2026The next daily point, and whether the 21 September reading is itself restated.
- Through October 2026Whether the pattern persists once the daily series has a longer history.
- Each 05:00 ETThe tape's RAPI mark, dated to the source's own newest point.
The story so far
- RAPI's 1-carat rises to $3,916.19 across five sessionsCorrected 22 September; the error that led to this check.
- RAPI 1-carat adds 0.59% since 8 August, now published dailyThe switch to daily publication that made restatement visible.
Go deeper
What would change this call
A stable read. If tomorrow's fetch returns these six points unchanged, what is reported here is a one-off revision rather than a standing property of the series.
How RAPI is put together
RAPI averages the asking prices of the ten per cent lowest-priced stones listed on RapNet within a narrow band, D to H colour and IF to VS2 clarity, GIA graded. It is a floor for a top specification rather than a market mean. Until 7 September the page published a monthly series; since then it has published a trailing thirty-day daily series per size. A daily average computed off a moving pool of listings can be recomputed as listings are added, withdrawn or regraded, and that is the ordinary mechanism by which a published point can change after the fact. Rapaport publishes no restatement policy on the page, and this desk is not claiming to know which mechanism applied here.
Method
The 22 September column was read from the index page's own embedded JSON series, parsed out of the raw bytes of a 200 response whose last-modified header read 22 September 2026 09:15:54 GMT, rather than from a rendered table or a summariser. The 21 September column is this paper's standards desk reading of the same URL, recorded in its own dated file on 21 September, before this article existed; it is an in-house record and is described as one rather than credited to Rapaport as a publication. No third party is credited with this comparison, because none has published one and none was consulted for it. The 16 September point has a third recorded reading, $3,912.13, which is what this paper's tape filed on 17 September and printed on 21 September; it is named here for completeness and is not used in the table, which compares only the two full-series reads. Every difference in the Move column is a subtraction of the two printed cells.