Presentation on theme: "Diamonds: Beauty and Brawn Carl Wozniak Graduate Gemologist (GIA) Northern Michigan University."— Presentation transcript:
Diamonds: Beauty and Brawn Carl Wozniak Graduate Gemologist (GIA) Northern Michigan University
The allure of diamonds The worlds love of diamonds started in India. Romans set uncut diamonds in jewelry By the 1400s, diamonds had become fashionable in Europe. Roman ring, 4 A.D.
Why the allure? Diamonds are cherished because: They are rare They are durable They are beautiful They have value They are expensive to mine and cut
Cutting Diamonds are extremely hard. In order to cut them, you have to use other diamonds. Rough diamond
Diamond anatomy A round brilliant cut diamond has either 57 or 58 facets.
What makes diamonds sparkle? A polished diamonds beauty lies in a complex relationship with the light around it. Facets on the stone reflect light externally and internally.
What makes diamonds sparkle? We see this interplay between light and the diamond in three qualities Brilliance- the degree to which light from within the stone returns to our eye Fire- the play of colors from the refraction of light within the stone Scintillation- the bits of light that flash as the stone is moved
Brilliance In brilliant stones, much of the light that enters leaves through the crown. Less brilliant stones result when light leaks out the pavilion.
Fire Fire, also known as dispersion, is the color play within a diamond caused by refraction of light in the stone.
Scintillation Scintillation is caused by light reflecting off the stones facets.
Grading diamonds Why grade diamonds? Diamond grading: Makes it possible to discuss diamonds simply and concisely; Helps you compare stones; Helps identify quality.
Grading diamonds The 4 Cs Color Clarity Cut Carat weight
Color While there are fancy colored diamonds that can be extremely expensive, typical diamonds increase in value as they get closer to colorless. The currently used grading scale was developed by the Gemological Institute of America A, B, C were not used to prevent confusion with existing scales. Hope Diamond ct., VS-1, Fancy deep grayish blue
Rule of thumb Colorless face up and face down D, E, F Colorless face up, nearly colorless face down G, H, I, J Faint yellow face up, faint yellow face down K, L, M Very light yellow face up and face down N, O, P, Q, R Light yellow (substantial) color face up or down S, T, U, V, W, X, Y, Z
Color Color is very difficult to judge in mounted stones Proper lighting is essential
Clarity Most diamonds come with some amount of junk inside them. We call these inclusions. Scratches and other surface imperfections are called blemishes. Before the 1950s people in the diamond industry had no way to accurately describe a diamonds features so that everyone understood them in the same way.
Clarity The GIAs diamond grading system was developed in 1953 to give professionals a way to evaluate diamonds and communicate quality to others.
Clarity Five clarity factors that determine the grade of a diamond Size of inclusion Number of inclusions Position of inclusions Nature of inclusions Color or relief of inclusions The clarity grade is not based on the sum of everything in the stone, but is based on the largest and most visible characteristics.
Clarity Grades Flawless (F) stones are exceedingly rare and never worn. Millenium Star, ct., D, Flawless Flawless stones have no visible inclusions under 10 X magnification, and there are no blemishes on the stones surface.
Clarity Grades Internally Flawless (IF) diamonds have the potential to become flawless stones. Internally flawless stones have no visible inclusions under 10 X magnification, but there are blemishes on the stones surface.
Clarity Grades Very Very Slightly (VVS) included diamonds Contain minute inclusions that are extremely or very difficult for a skilled grader to see under 10 X. VVS 1 = extremely difficult to see face up (one or two pin points) VVS 2 = somewhat easy to see
Clarity Grades Very Slightly (VS) included diamonds Contain minor inclusions that are difficult to easy for a skilled grader to see under 10 X. VS 1 = difficult to see inclusions VS 2 = somewhat easy to see Typically small crystals or feathers near the edge.
Clarity Grades Slightly Included (SI) diamonds Contain noticeable inclusions that are easy or very easy for a skilled grader to see under 10 X. SI 1 = easy to see inclusions SI 2 = very easy to see. Eye visible. Typically crystals, feathers or clouds centrally located.
Clarity Grades Included (I) diamonds Contain obvious inclusions to a skilled grader under 10 X. I 1 = quite visible inclusions I 2 = easily visible I 3 = extremely visible. Affects the stones durability. I-2 I-3
Cut Diamonds can be cut in many different shapes, but this is not all we mean by cut. Cut refers to not only the shape of the diamonds, but its proportions and finish, factors which determine the sparkle of the diamond.
Cut Round brilliant cut diamonds have been studied the most. They are the most common The proportions are relatively consistent
Misalignment of facets, misshapen facets, and pointing problems go hand-in- hand. Where you find one, youll usually find the others.
Carat weight Diamonds weight is measured in carats. 1 ct. = 1/5 gm. 1/100 ct. = 1 point
Carat weight Rule of Thumb 1 All other things being equal, the bigger the stone, the more expensive it is.
Carat weight Rule of Thumb 2 Cost jumps dramatically at magic sizes.
The care and feeding of diamonds Diamonds have a high affinity for grease. Rough diamonds are actually sorted using grease tables. Grease changes the refractive index of the stone, causing light to leak out the pavilion.
The care and feeding of diamonds Use an old toothbrush and soapy water to clean under the stone. Can also use ultrasound or steam Keep gold jewelry away from chlorine bleach.
Synthetic diamonds Synthetic diamonds are becoming more common, but they are usually small stones, yellowish stones. Diamonds are made under temperatures of about 2,200º F and 50,000 atmospheres.
Synthetic diamonds Cremated remains can be made into diamond.
Common Diamond Simulants Cubic Zirconium (Zircon Oxide) CZ has slightly less brilliance or sparkle than a diamond and more fire or flashes of color CZ also comes in many colors.
Common Diamond Simulants Telling CZ from diamond About 75% heavier than diamond CZ is softer, you see this in abraded facet junctions Orange pavilion flash Usually flawless Many colors Thermal conductivity
Common Diamond Simulants Moissanite- Silicon carbide Has inclusions and color differences Similar thermal conductivity Very hard Slightly lighter than diamond Moissanite has a lot more fire than diamond.
Common Diamond Simulants Moissanite- Silicon carbide But, moissanite is strongly doubly refractive
A little knowledge will make you a better consumer. Youre invited to clean and examine your own stones.