The Aguilar 990 belt that isn't in the Morrill book

In September 2024, John Moran Auctioneers in Monrovia sold a Hector Aguilar "Georgia O'Keeffe" concho belt — four X-form silver conchos on black suede, the iconic 1940s design worn by the painter in her studio photographs — for $2,244, nearly three times its $800 high estimate. Two months later, a second specimen of the same belt sold for $1,716 at the same house.

What made the first of those two belts unusual enough to draw the premium is recorded in a single line of the catalog description: "Buckle and one concho stamped: HA / Taxco / 990."

Every other Hector Aguilar concho belt with visible hallmarks in the public auction record reads 940, not 990. That single-digit difference is the subject of this piece.

What is the Georgia O'Keeffe concho belt?

Hector Aguilar (1905–1986) ran the Taller Borda in Taxco from 1940 until 1962, the largest silver workshop in Mexico at its peak, with some forty craftsmen working under him. His X-form concho belt — silver crossed-arm ornaments mounted at intervals on black suede, closing with a plain hooked silver buckle — entered American visual culture through Georgia O'Keeffe, who wore one (or a near-twin) in several of the studio portraits taken at her Abiquiú home in the 1950s and 1960s. The belt is now so closely associated with her that auction houses cue it that way by default: in our database of forty-five Aguilar belt lots, roughly a quarter carry "Georgia O'Keefe" in the title.

Morrill's Mexican Silver does not picture this specific belt, but it walks Aguilar's marks in detail. From p. 101:

Hector Aguilar's hallmark originally was in the style of Spratling's, a simple attached "HA" in an indented circle. On either side were the marks, "Taxco" in block letters and "940" in a rectangular indentation (Pl. VII-26). Occasionally the early "HA" appeared with the words, "Made in Mexico" and "Sterling" (Pl. VII-4b).

The early period — the one that matches the documented 1940–1945 date range on the surviving O'Keeffe belts — is consistently "HA + Taxco + 940." Morrill's Chapter XXVII hallmark gallery (pp. 242–247) does not include any Aguilar mark stamped 990. Neither does the reference list of Golden Age maker marks on pp. 245–247.

How many Aguilar belts are stamped 990 instead of 940?

Among forty-five Hector Aguilar belt lots in our pool (from John Moran, Heritage, Bonhams, Bourgeault-Horan, Palm Beach Modern, MBA Seattle, and several smaller regional houses going back to 2009), the hallmark readings divide cleanly:

• Forty-three lots: stamped "940" (or ".940," or "Sterling" for the earliest examples that predate the standardized purity number)
• Two lots: stamped "990" instead of "940," with no other distinguishing variation in design or materials

Those two are:

1. John Moran, September 11, 2024, lot 2096. A "Georgia O'Keefe" concho belt, c.1940–1945. Buckle and one concho stamped HA / Taxco / 990. Estimate $800–1,200. Hammer: $2,244. (Catalog.)
2. John Moran, 2024 via LiveAuctioneers. A second "Georgia O'Keefe" concho belt, c.1940–1945, same stamping pattern. Hammer: $1,700. (Catalog.)

Both describe the physical object in essentially identical terms: four X-form conchos alternating with large silver rivets set on black suede, approximately 25–28 inches long, 247 grams for the dated lot. The belt shown at the top of this post is lot 2096.

What does 990 mean on Hector Aguilar silver?

The tempting reading is that 990 is a silver-standard mark — the same kind of three-digit purity code that 940 (94% silver) and 925 (sterling) are. On an Aguilar piece that would be a significant upgrade. Morrill records that Aguilar's standard output was 940 silver, so a 990 mark would indicate a rare, exceptionally high-purity batch — hence the "990-silver" framing that circulates in collector forums.

That reading probably isn't right, and the reason is embedded in the John Moran catalog descriptions of other Aguilar lots. Consider this excerpt from a 2024 grouped-jewelry lot:

Each variously stamped: HA [conjoined] / Taxco / 940 / [Eagle 9] / 990 / Made in Mexico / Sterling

The same pieces carry 940, 990, and Sterling simultaneously. A single object cannot be three different silver standards at once. If 990 were a purity number, it could not coexist on the same stamp cluster as 940 and Sterling.

A more plausible reading is that 990 is something other than a purity claim — perhaps an inventory or workshop batch number analogous to the letter-and-digit inventory codes that Kim Richter documents for Antonio Pineda in Silver Seduction (p. 81), where Pineda stamped form-factor codes like 99 (rings), 89 (brooches and pins), 82 (buckles), 77 (necklaces), and 22 (bracelets). Aguilar would not have used Pineda's exact scheme, but a parallel workshop convention is a natural explanation for a three-digit code that appears alongside, rather than in place of, the silver standard.

The honest answer is: we do not know what 990 means on a Hector Aguilar piece. Neither Morrill nor Stromberg documents the mark, and the pattern of its appearance on other Aguilar silver — alongside 940, not replacing it — suggests the simple purity-claim explanation is unlikely.

Are 990-stamped Aguilar belts worth more?

Comparable "Georgia O'Keeffe" concho belts stamped 940, which is every other documented example, sold in our auction pool between $425 and $1,716, with a typical hammer in the $700–$1,100 range. The two 990-stamped lots sold for $1,700 and $2,244.

A sample of two is not a trend. But it is noticeable that in each case the catalog description flagged the 990 mark explicitly, and in each case the hammer exceeded the house estimate by a meaningful margin. Collectors who paid those prices were paying, in part, for a mark they could not cross-reference in any canonical literature.

Do you own an Aguilar piece stamped 990?

This piece is a first public attempt to document what 990 means on Hector Aguilar silver. If you own, have sold, or have photographed an Aguilar piece stamped 990 — belt, brooch, necklace, cuff, anything — the Museum of Mexican Silver would like to hear from you. A few specific questions that would help:

• What else is stamped on the piece? The hypothesis that 990 is an inventory or batch code predicts that 940 (or Sterling) will also appear on most or all examples. A counter-example, where 990 appears as the only purity-like number, would complicate that reading.
• Is there a date range where 990 clusters? The two belts are both catalogued c.1940–1945. If 990 is a short-lived workshop convention, other stamped pieces should fall in a similar window.
• Does 990 correlate with a specific workshop subgroup? Aguilar's Taller Borda was large. Different maestros may have used different inventory conventions within the same roof. Taller Borda itself is occasionally marked separately (Morrill p. 101).

We will update this post as new 990-stamped Aguilar pieces surface in the auction record. The goal is a short running inventory of documented examples that scholars and auction houses can reference.

Sources

• Penny Chittim Morrill and Carole A. Berk, Mexican Silver: 20th Century Handwrought Jewelry & Metalwork (Schiffer, revised). Hector Aguilar chapter, pp. 97–111; mark description at p. 101; Chapter XXVII hallmark gallery and reference list, pp. 242–247. None of the cited marks, figures, or reference-list entries include a 990 stamp on Aguilar work.
• Gobi Stromberg, Silver Seduction: The Art of Mexican Modernist Antonio Pineda (Fowler Museum at UCLA, 2008). Kim Richter, "A Chronology of Pineda's Hallmarks," pp. 79–81. The Pineda inventory-code system described at p. 81 is the parallel most likely to clarify what 990 means on Aguilar silver.
• John Moran Auctioneers, September 11 2024, lot 2096 — Hector Aguilar "Georgia O'Keefe" concho belt with 990 stamp. Sold $2,244 against $800–1,200 estimate.
• John Moran Auctioneers, 2024 via LiveAuctioneers — Hector Aguilar "Georgia O'Keefe" concho belt with 990 stamp. Hammer $1,700.
• John Moran Auctioneers, October 2024 — grouped Aguilar jewelry lot illustrating "940 / 990 / Sterling" all stamped on the same pieces.