$687 a carat: lab-grown's one-dollar drift becomes a thirteen-dollar step

§1The lowest reading this tape has carried.

The one-carat lab-grown reference this paper carries fell to $687 on 1 September, from $700, a drop of $13 or 1.8571% in a single session. The figure is CaratRadar's average asking price for a one-carat lab-grown stone, read directly from the page by this desk, which carries its own dateline of 1 September and reports 1,204,718 active listings behind it. It is the lowest reading in this tape's record, and that record begins on 5 August 2026, so the claim is scoped to twenty-one sessions and no further. What makes it worth a page is not the level but the size of the step.

§2A month of ones and twos, then a thirteen.

Until this morning the series had one shape and it was a drift. The mark peaked at $711 on 8 August and came down in ones and twos: $710, $707, $705, $704, $703, $701, $700. Across the whole of that run the largest single-day move was three dollars, on 14 August, which was 0.4225%. Today's move is $13, four and a third times the largest daily fall the series had previously produced, and it comes after two sessions at $700 in which nothing moved at all. Cumulatively the reference has lost $24, or 3.3755%, since the 8 August high. Most of that was accumulated a dollar at a time over three and a half weeks; more than half of the last week's loss arrived this morning.

§3The natural side is on a different clock.

The natural side is not moving with it, and the honest thing is to say that the two cannot be compared day to day. This paper's RapNet Diamond Index mark is a monthly figure and still carries its 24 July date, so there is no natural reading for 1 September to set against this one. The most recent natural data this desk can point to is Rapaport's Diamond Pulse newsletter published in early August, which reports July rather than August: one-carat prices staged a broad turnaround in July, reversing June's declines across nearly every category, with K-M VS stones moving from a 0.1% loss to a 2.8% gain, D-F SI declines narrowing to 0.2% from 2.1%, and G-J SI reversing to a 0.2% gain from a 0.3% decline. That is a month old and it is natural goods, not made ones. Set beside a lab-grown series that has not posted a single up day since this tape opened, it describes two markets that have stopped rhyming.

§4Three numbers, none interchangeable.

One caution for anyone pricing off this, because the trade routinely quotes three different numbers as though they were one. The $687 here is an average asking price for a finished one-carat stone in a retail-facing listings pool. The chip on this site's own tape reads $475, and that is a different thing again: the midpoint of the published CVD wholesale band for a one-carat D-F VS stone. This paper's lab-grown price list carries a third, $545 the carat as a retail ask. None of the three is wrong and none of them substitutes for another.

A merchant reading a 1.86% fall in the listings average should not assume the same fall has reached the wholesale band, which moves on a slower clock and is republished rather than ticked.