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What an Amazing…Brown Diamond?

What an Amazing…Brown Diamond

It was a hot August day and I was trolling the antique stores on Charles Street in Boston for a deal.  The state of Massachusetts had declared a sales tax free weekend and I was looking to take advantage of it by investing some excess cash in antique jewelry or loose diamonds.  I had one antique store in particular that I favored for this sort of expedition.  I won’t name the shop, but it was a hole in the wall that had a good selection of antique jewelry and loose diamonds at reasonable prices.  After entering, I asked the proprietor behind the counter to show me everything he had.  After searching through his vintage jewelry with no luck I quickly moved onto his stock of loose diamonds.

I don’t know what his sources were, but he did brisk sales in loose stones.  Business was traditionally slow in August though, when a lot of dealers and customers went on vacation.  I think that is how I got lucky, finding a stone that I not only liked, but adored.  It was an off-color, old mine cut diamond of around 1.71 carats with good clarity.  It was a very fine stone in spite of its brown color, with superb fire and a great deal of warmth and charisma.  The diamond was undoubtedly at least a century old and possessed an ethereal charm that was difficult to put into words.

The price was almost too high for me to consider though, even without sales tax – about $2,000.  I asked the proprietor if his store would be open the next day and he answered affirmatively.  I then told him I might return tomorrow to buy the stone.  He peered at me suspiciously over his glasses and commented skeptically, “Sure, if you come back.”

Later, after I returned home, I told my wife I had found something absolutely amazing during my antiquing expedition.  Our exchange went something like this:

“What did you find?” asked my wife curiously.

I fumbled desperately in my mind as to how to reply before I resigned myself to reluctantly telling her the unpleasant truth.  “It’s a brown diamond,” I said sheepishly.

“A brown diamond?” echoed my wife incredulously.  “Why in the world would we want a brown diamond?”

“Well, brown isn’t quite the right word for it,” I protested weakly.  “You really have to see it to truly appreciate it,” I continued undeterred.  “Why don’t you come with me to the antique store tomorrow and we’ll look at it together.  If you aren’t impressed with the diamond, then we won’t buy it,” I offered timidly.

To my great relief at the time, my wife agreed to my proposal.  The next day I withdrew some money from the ATM and off we went to the antique store.  As we set foot inside the venerable establishment I realized just what a terrible bargain I had made with my wife.  The interior of the shop was not exactly conducive to selling…well…anything.

Pieces of dusty antique furniture were haphazardly stacked on top each other to form narrow aisles that forced customers to carefully navigate the store in single file.  The lighting was absolutely awful.  The cathedral ceilings were set with distant, tube-style florescent lights that cast a dim, clinical and solemn pallor over everything in the store.  The only natural light shown faintly from some extremely dirty plate glass windows on the far side of the store, partially obscured by mountains of old furniture and jumbles of miscellaneous antiques.  There wasn’t even a small table lamp to use as a makeshift spotlight on the store’s counter.  I immediately broke out into a cold sweat.  No gemstone, regardless of how amazing it might be, could possibly look good in this charnel lighting.

After quick introductions with the shopkeeper, he pulled out the paper parcel containing the stone and handed it over to me for examination.  I carefully unwrapped the color-challenged gem with much trepidation.  My spousal reputation was on the line here, not to mention the possibility of acquiring the coveted stone.  And then the diamond tumbled out in front of us, sparkling, sublime and supremely confident in its own immutable beauty.

My initial thought upon seeing the stone again was “Koh-i-noor,” referencing the famous Indian diamond now residing in the British Crown Jewels whose name translates from Persian as “Mountain of Light”.  The diamond in front of us was one of the most gorgeous stones I had ever laid eyes on.  It possessed an intense fire that is almost never seen in modern-cut stones.  Even in those drab surroundings, with the worst lighting imaginable, its facets sparkled seductively with delicate flashes of peach, pink, and salmon.  The diamond’s questionable brown hue was really closer to a light golden color than I had remembered as well.  Under normal circumstances, any tinge of color decreases the value of a white diamond, but this stone was intense enough that it could potentially be graded “light fancy” according to the GIA color scale – a very desirable trait.

Words truly did not do the gem justice, especially the word “brown.”  To my great relief, my very sensible wife was equally impressed.  After 15 minutes of negotiations we walked out of the antique store as proud owners of a fine, 1.71 carat, old mine cut, brown diamond.  It was one of the best antique purchases I ever made.  The stone is today undoubtedly worth substantially more than I paid for it, but I have no plans to sell anytime soon.  I think the lesson of the brown diamond is clear.  Sometime you just have to see an antique in person before you make a definitive judgment on it.  Sometimes brown isn’t as ugly as it sounds.

Of Karat Gold and Noble Nuclei

Of Karat Gold and Noble Nuclei

Gold is omnipresent in the world of investment-grade art.  Serious connoisseurs of art and antiques frequently encounter items made either partially or entirely from gold.  This isn’t surprising considering gold is a premier luxury material.  The yellow precious metal has been lavishly used in everything from high-end jewelry to luxury watches to vintage fountain pens to breathtaking objets d’art.

Gold purity in jewelry and other antiques is usually measured in karats, with 24 karats representing pure gold.  Gold alloys commonly encountered are 18 karat (75%) gold, 14 karat (58.3%) gold and 10 karat (41.67%) gold.  In addition to the aforementioned alloys, British antiques and jewelry can sometimes be 22 karat (91.67%) gold, 15 karat (62.5%) gold or 9 karat (37.5%) gold.

Now a question that we might naturally ask ourselves as investors in antiques is which of these alloys is acceptable and which aren’t?  At what point is a gold alloy too diluted to qualify as “investment-grade” anymore?  The short answer is “the point where the gold alloy stops acting like gold.”  In other words, how low can one descend the karat ladder before your gold alloy becomes vulnerable to corrosion and tarnish?  Another important factor is that low purity gold alloys have difficulty achieving an intense, true gold color.

In order to determine a reasonable lower bound for acceptable gold purity, we need to understand a basic, fundamental law of gold alloys that is not widely known.  A gold alloy’s corrosion resistance is closely related to the percentage of gold atoms it contains.  The higher that percentage, the more the alloy will behave like pure gold.

Any other precious metal atoms in the alloy (usually silver, although palladium is sometimes an alloying agent in white gold) also help enhance corrosion resistance, although not to the extent that gold does.  Precious metals are sometimes referred to as the noble metals because of their chemical inertness.  Therefore, we want a gold alloy to not only have a high percentage of gold atoms, but also a high percentage of noble metal atoms – aka noble nuclei.

So, even though we know the percentage of our alloy that is gold by weight, this isn’t the information we need.  We must convert this proportion by weight to proportion by number of atoms.  Luckily, we can derive this information with a bit of math and science, assuming we know all the constituents of the alloy in question.  The formula we’re going to use for this is below:

 

Number of Atoms = (Percentage of Element in Alloy x Avogadro’s Constant)/Atomic Weight of Element

 

Avogadro’s number (6.022141527 × 10^23) allows us to estimate the number of atoms, molecules or ions in any substance provided we know its mass and molecular or atomic weight.  To make this calculation work we also need to know the atomic weights of metals commonly found in yellow gold alloys for our calculations.  However, in this case, we can ignore mass because we only care about the ratio of gold to its other alloying constituents.

Now if we plug the various numbers for a typical 18 karat yellow gold alloy (75% gold, 12.5% silver and 12.5% copper by weight) into the formula above we get the number of atoms each element contributes to the alloy.  Then, using a little more simple math we find the relative proportion of each element in the alloy in terms of number of atoms present, instead of by weight, which is how alloys are usually represented.

In this case, our 18 karat yellow gold alloy is composed of 54.92% gold atoms, 16.71% silver atoms and 28.37% copper atoms.  The noble nuclei (gold and silver) together are fully 71.63%.  The very high percentage of noble nuclei – and gold nuclei in particular – give this alloy excellent corrosion resistance and a rich, deep gold color.

You may have noticed that the proportion of any element’s atoms is inversely correlated to its atomic weight.  In other words, very large atoms – like gold – tend to contribute fewer atoms to an alloy than their percentage by weight in the alloy would suggest.  Conversely, smaller atoms – like copper – will contribute more atoms to the alloy than their percentage by weight would imply.

Now let’s make the same calculations using a typical 14 karat yellow gold alloy consisting of 58.3% gold, 12% silver, 19.7% copper and 10% zinc by weight.  The percentage of gold atoms contained in this 14 karat yellow gold allow has now declined to 34.01% while the noble nuclei have dropped to 46.80%.  This 14 karat gold alloy, although possessing slightly less desirable properties than its 18 karat gold counterpart, will still have good corrosion resistance and a pleasing yellow-gold color.

Let’s try this one more time, this time using a typical 9 karat yellow gold alloy composed of 37.5% gold, 10% silver, 45% copper and 7.5% zinc by weight.  The percentage of gold atoms has declined precipitously to 17.22% in this 9 karat yellow gold alloy.  Even the level of noble nuclei has dramatically fallen to 25.60%.  This gold alloy will be inferior, with poor corrosion resistance and a pale, washed out yellow color.

Once a gold alloy declines below 30% to 35% gold atoms or 35% to 40% noble nuclei, it starts to look and behave much more like its constituent base metals than gold.  This transition occurs right around the 14 karat mark.

Once a gold alloy dips below this level, even to just 12 karats, its physical properties rapidly deteriorate.  Lower karat gold alloys like 9 or 10 karat are simply lost causes.  No matter how you manipulate their component elements, it’s impossible to get an alloy that has good color and good corrosion resistance.

The conclusion is clear: only buy 14 karat gold or better jewelry for investment purposes; avoid anything lower.  This sage advice is echoed by the quality distribution apparent in fine jewelry as well.

18 karat gold alloys and above have traditionally been exclusively restricted for use in very high quality jewelry.  14 and 15 karat gold is the middle ground, where workmanship can vary tremendously, ranging from mediocre to excellent.  Lower karat gold alloys – like 9 and 10 karat gold – have traditionally been reserved for mass-produced items with little regard for quality.

Purple Gemstones – The Color of Royalty Resurgent

Purple Gemstones - The Color of Royalty Resurgent

For most of recorded human history, purple was the original power color. It was the color of kings, queens, emperors and royalty. In the 1st century AD, Roman emperor Nero not only decreed that purple garments were reserved solely for the emperor, but also that trade in any purple items was banned – on pain of death!

In the 6th century AD, when an uncontrollable riot almost forced the Byzantine emperor Justinian I to flee, his consort, the empress Theodora, gave him courage by boldly declaring that “Royal purple is the noblest shroud.” Royalty has jealously guarded the majesty of purple for millennia.

For ancient and medieval peoples, purple represented the very pinnacle of color, a natural pairing to sovereigns. And no gem dripped more decadently with that elusive, royal color than coveted amethyst. The ancient Greeks believed the purple stone could prevent intoxication. In fact, amethyst comes from the Greek term “not drunk.” For centuries, amethyst was one of the most expensive gems on the planet, considered the equal of diamonds, rubies, sapphires and emeralds.

All that changed in the early 19th century, however, when massive deposits of the previously rare gem were found in Brazil. Prices plummeted almost overnight. By the late Victorian era, amethyst was considered far too plebian for the jewelry of the aristocracy, much less that of royalty, although it was still employed in some fine Arts and Crafts and Art Nouveau jewelry.

The second half of the 20th century was even less kind to once coveted purple gemstones. Calibre-cut amethysts were often used as inexpensive additions to low-value, mass-produced tennis bracelets, earrings and cocktail rings. Amethyst’s harrowing descent from noblest gem to lowly bauble mirrored purple’s demotion from the color of royalty to just another banal hue.

Fine jewelry largely ignored purple gemstones throughout most of the 20th century, instead gravitating towards the bold, thrilling reds of rubies, the enigmatic, soothing blues of sapphires and the dazzling, brilliant white of diamonds. But then a funny thing happened. It gradually dawned on gemstone connoisseurs that three exceptionally fine stones came in purple: sapphire, spinel and tanzanite.

One of the many different hues of fancy sapphire, purple sapphire had been inexplicably overlooked by the gem industry for many decades. Sapphire, with its incredible brilliance, fire and hardness, is the consummate colored gem. So it isn’t surprising that a renewed interest in purple sapphire has recently brought this ravishing gem to the forefront of fashion. This newfound enthusiasm has pushed purple sapphire prices skyward. Whereas 1 carat stones used to trade for around $50 per carat, now you would be very lucky to find decent stones at $200 or $300 a carat.

Purple sapphire’s sister stone, purple spinel, has also seen a wave of interest in the last couple of decades. In addition to being almost as hard and tough as sapphire, spinel possesses a rare and treasured trait among colored gemstones; it is never treated. This means that every (non-synthetic) spinel is an all-natural stone, mined directly from the earth with no need for artificial enhancements to bring out its tremendous beauty. These underrated gemstones are a bargain compared to purple sapphire, with fine specimens still available at under $100 a carat.

Tanzanite is a relative newcomer to the world’s stage. Only discovered in 1967, tanzanite is a striking violet-blue stone that is mined in only one location on earth – Tanzania. The gem’s similarity in color to blue sapphire – except with a strong hint of purple – has made it a hit among gem collectors and jewelry lovers alike.

In fact, the gem is so beautiful that the first company to promote the new gem shortly after its discovery was none other than renowned luxury house Tiffany & Co. Sadly for tanzanite enthusiasts, experts estimate that its single source mines have perhaps only 15 to 20 years of production left before they are completely exhausted.

As recently as 20 years ago, all purple gemstones was invariably assumed to be a cheap and garish amethyst. Consequently, purple gemstone jewelry was largely viewed as mundane costume jewelry. But this misinformed attitude is rapidly becoming a thing of the past. Today’s high power purple gemstones – sapphire, spinel and tanzanite – are all exceedingly rare, incredibly desirable and more popular than they’ve ever been before. Purple gems are back, but this time around they aren’t just for royalty.