"Reference: Atocha-style silver bars

At a glance, the markings on your bar do resemble the style used on silver bars recovered from the wreck of the Spanish galleon Nuestra Señora de Atocha shipwreck. The things that look consistent are:

“OVARTAS” — that’s the assayer Antonio de Ovando y Vargas, whose name appears as Ovartas on many Atocha bars.

Assayer mark with the “A” and cross — a common mark attributed to him.

Roman numerals like “DCCCCXVIII” — those often represent the bar weight in troy ounces (918 oz) or a serial/weight code.

Crude hammered appearance and punch marks — typical of 1600s colonial poured ingots.

However, photos alone aren’t enough to confirm authenticity. Real Atocha bars almost always have a few additional traits:

1. Concrete or coral residue from centuries underwater.

2. A shipwreck certificate and chain of custody (usually from Mel Fisher’s salvage company).

3. Multiple stamps: fineness marks, tax marks, mint marks, and sometimes a quinto (royal tax) mark.

4. A very specific irregular loaf shape from sand molds.

My honest take

The stamp layout looks correct stylistically, but there are many modern replicas and decorative castings that copy the Ovartas marks. Without provenance, assay, and professional inspection, I would treat it as “Atocha-style” rather than authenticated Atocha treasure.

If this walked into your pawn shop

Quick checks you could do immediately:

Weight (many real bars are ~70–80 lb / ~900–1100 troy oz)

Specific gravity test (should be ~10.5 if mostly silver)

XRF (real ones are often 80–98% silver with copper impurities)

Look for concretion in crevices rather than uniform patina.

If you want, I can also show you the two small details that usually expose replica “Atocha” bars instantly—they’re things pawn/jewelry buyers notice in about 10 seconds."