Assay Jewelry

Assay Jewelry Rare gems. Rare watches. Real knowledge. ASSAY is a curator of certified colored gemstones, diamonds and luxury watches with provenance.

We source pieces you won't find anywhere else — and we've been doing it since 1983. GIA Graduate Gemologist on staff.

09/04/2026

Not everything that’s special has to be expensive.

Search “Star Of David” or these sku numbers on the website. DM us for the link.

SKU - GA2034-3 (Ruby)
SKU - GA2034-1 (Diamond)

09/04/2026

A heart-cut emerald is a rare sight, especially at this scale and quality.

Most emeralds are cut as emerald cuts because the shape follows the rough efficiently, helping preserve valuable carat weight.

SKU - J17810N

Four blue sapphires. Four completely different personalities. 💙From Ceylon and Thai origins to rare no-heat stones, each...
09/03/2026

Four blue sapphires. Four completely different personalities. 💙

From Ceylon and Thai origins to rare no-heat stones, each ring brings its own shade, setting, and character.

Item numbers and details in order:

1. POTC2648 - GIA Certified 6.03 Carat Oval Ceylon Sri Lanka Sapphire & Diamond Platinum Ring

2. GA2309-2 - GIA Certified 4.15 Carat Oval Thai Sapphire & Diamond Vintage Platinum Ring

3. GA0584-2 - 7.70 Carat No-Heat Blue Sapphire & Diamond Ring Convertible to Pendant

4. GA0586 - Vintage 2.38 Carat No-Heat Oval Blue Sapphire & Milgrain Finish Diamond Ring

Which blue catches your eye first?

Comment 1, 2, 3, or 4 below.

DM us the item number for more details.

09/01/2026

Follow before you buy your next diamond, because this could save you thousands.

Never buy a natural diamond without asking your jeweler one question: is it fracture filled?

Fracture filled diamonds had a crack, and glass was injected into it under pressure to make the crack far less visible. Look closely and you’ll see long straight lines inside the stone, almost like a flash of light trapped in glass. That’s the tell.

It doesn’t mean the stone is worthless. It means it’s worth less, and you should be paying accordingly.

Screenshot this before your next diamond purchase.

08/31/2026

Cartier made more than just jewelry. They made this.

This one sold quick! DM us if you want to join our newsletter with weekly new arrival updates

A solid sterling silver bugle horn charm, gold plated, signed Cartier.

08/30/2026

Follow and comment “diamond” and I’ll DM you 5 step checklist to see if a diamond is color treated.

$20,000 and $180,000. Both of these are natural diamonds, and both are yellow.

Screenshot this part before you keep scrolling.

    •    Natural color diamonds form their yellow in the ground with no treatment.
    •    Treated color diamonds go through HPHT, high pressure and high temperature, which changes the stone’s structure and shifts it to yellow.
    •    A treated diamond is still 100 percent a natural diamond. It has simply had its color enhanced.
    •    The treatment is permanent and must be disclosed on the certificate.
    •    GIA reports list this under “color origin,” stating either natural or treated.
    •    Treated stones cost far less because untreated color at this intensity is rare.

Follow and comment “diamond” for the full guide on spotting the difference.

Swipe to discover four vintage Rolex watches in gold. ✨From the classic Oyster and Datejust to the elegant Orchid and Pr...
08/28/2026

Swipe to discover four vintage Rolex watches in gold. ✨

From the classic Oyster and Datejust to the elegant Orchid and Precision, each piece showcases a different side of vintage Rolex design.

Item numbers and details in order:

1. POTC2165W - Rolex Oyster Ref. 1005 Ch*****ne Dial Gold Vintage Watch

2. 2005 - Rolex Orchid Ref. 2673 18K Gold 22mm Diamond Bezel 1989 Watch

3. POTC2581W - Vintage Rolex Datejust President 26mm 18K Gold Ch*****ne Dial Fluted Watch

4. POTC2414W - Vintage Rolex Precision 22mm 18K Gold Ch*****ne Dial Manual Wind Watch

Which vintage Rolex would you choose?

Comment 1, 2, 3, or 4 below.

DM us the item number for more details.

08/25/2026

A $100 ruby and a $4,000 ruby. Both are real.

Comment TEACH ME and I’ll send you the full guide.

The cheap one is glass filled. It started as ruby so fractured nobody could sell it, so lead glass was poured into every crack until the fractures disappeared.

You can catch it yourself with a $20 loupe. Bright light, tilt it slow, look for round bubbles trapped inside the stone. Rubies don’t grow bubbles. Glass does.

And it matters after you buy. A jeweler’s torch during a resize can wreck the filler. So can lemon juice.

Heat is fine. Glass is a deal breaker.

08/25/2026

It’s called invisible setting, developed in Paris in the 1930s.

This is a French Art Deco vanity box from around 1930, 20 carats of Burma ruby, 181 grams of

Each stone is grooved along its base and slid onto a hidden rail underneath, so the metal sits below the surface where you cannot see it.

SKU: POTC2657
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Address

169 East Flagler Street
Miami, FL

Telephone

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