Question Regarding Diamond Scintillation

[Mark_Jack53]

Greetings to everyone who reads this message,

To begin, I am new to this community. I am also a diamond novice in need of some advice. I am currently on a quest to find a diamond for an engagement ring. I have come across a stone (GIA: Excellent cut, symmetry and polish) which I have viewed in person and it looked great. For those who are experienced at grading diamonds from a GIA report; how much sparkle would I be expecting from a diamond with these measurements?

ROUND BRILLIANT
-Measurements
4.74 - 4.77 x 2.94 mm
-Carat Weight
0.41 carat
-Colour Grade
F
-Clarity Grade
VVS1
-Cut Grade
Excellent

PROPORTIONS
-Depth
61.9 %
-Table
58 %
-Crown Angle
36.0°
-Crown Height
15.5%
-Pavilion Angle
40.6°
-Pavilion Depth
43.0%
-Star Length
50%
-Lower Half
80%
-Girdle
Medium, Faceted, 3.5%
-Culet
None

FINISH
-Polish
Excellent
-Symmetry
Excellent

FLUORESCENCE
-Fluorescence
Medium Blue

CLARITY CHARACTERISTICS
-Clarity Characteristics
Pinpoint

Thank you so much, I would be appreciative of any replies.
Kind regards,
Mark.

 

[OoohShiny]

It all gets a bit technical once you start looking at angles and measurements...

The easiest thing is to put the numbers into the HCA tool (under the Tools tab at the top of the forum) and find out what it scores. If under 2, that indicates the angles might work well together.

I've not done that for you but I think this should score pretty well.


What is your budget? Do you have specific colour/clarity/carat weight expectations/requirements?

 

[Mark_Jack53]

Hello OoohShiny,

I scored it using the HCA and it gave 1.9 - which fell in the excellent grade. I am from the UK, where I was quoted £1250 (Inc VAT) for the stone at 0.41 carats. Value for money is my concern at the moment. The total ring price quote was £1850, which I found reasonable. However, I'm struggling to know if I'm getting ripped off in the diamond department.

I have viewed the diamond in person, but obviously, I am no expert, so it just looked sparkly to me... I viewed it against a similarly sized diamond (VS2). However, the VVS1 was noticeably more brilliant and fiery. Looking at the GIA certificates, the VS2 had a feather, cloud and crystals (But scored better on the HCA)... whereas the VVS1 only had pinpoints within it.

Thank you for taking the time to reply!

 

[OoohShiny]

Welcome, fellow UKer

Good news on the HCA front!

You would need an ASETscope image to understand how accurate the cutting is (in terms of symmetry, leakage, twisted pavilion facets, etc.) but here in the UK, they are either unheard of or viewed very cynically, it seems...

Don't forget that is the angles and facets within a diamond that creates sparkle and fire, not the clarity - clarity is a mere side note in many ways. After all, the window in the room you are in is colourless and flawless, but does it sparkle? No, because it's been 'cut' to let all the light through, rather than collect, disperse and reflect it back

I think the VVS1 above is fiery because it has a high crown angle - 36% - which increases the size of the facets on the top of the diamond, which go round the table. These facets disperse the light coming out of the diamond into 'rainbow fans' (which is the coloured 'fire' when it passes over your eye) so a higher crown stone usually is more fiery, I believe.

You must also take account of the fact that stores spend a great deal of money on lighting that makes even poorly cut diamonds look great so it is good to ask to view stones in a 'flat' light, like a cloudy day (not that we get many of those... lol).


In terms of price comparisons, I think you've done well to find what you have (re: a decent HCA score). You can check out comparable stones on the search tool at the top of the forum - this link is for AGS000 stones only, which are basically mostly guaranteed to perform well (because AGS measures light performance during the grading process):
https://www.pricescope.com/diamonds/search?vendor=-1&branded=None&inhouse=-1&shape=1&minprice=1&maxprice=1500&mincarat=0.4&maxcarat=0.6&mindepth=0&maxdepth=100&mintable=0&maxtable=100&mincut=1&maxcut=1&mincolor=1&maxcolor=3&minclarity=2&maxclarity=7&minsymmetry=1&maxsymmetry=8&minpolish=1&maxpolish=8&min_cut_gia=1&max_cut_gia=6&min_cut_ags=1&max_cut_ags=7&minflourescence=1&maxflourescence=6&checkbox_panel1=,02&checkbox_panel2=&sort=&page=1&pageview=24&adv=false&days=100&cert_number=

Prices are in US$ but with exchange rates and then 20% VAT on importing a loose stone (+another 2.5% if it's set into a ring, IIRC) you can basically convert US$ to GBP and come out at the same figure - so, to me, the Whiteflash 0.42 F VVS1 looks like a strong contender


In terms of GIA XXX stones, there are a LOT around that price/size (because 0.5ct is a 'magic mark' and cutters aim for it to increase profits) but it looks like you could potentially even get to a 0.58ct stone - careful selection would be needed, though...:
https://www.pricescope.com/diamonds...=1&pageview=24&adv=true&days=100&cert_number=

 

[Mark_Jack53]

Thank you for your reply once again!

Yes, it seemed to me like a decent enough offer to view and buy without any hassle. The HCA score is promising, especially as there will be no imperfections (such as clouds and feathers) which could alter the travel of light. Thank you for taking the time to analyse the angles, but it was the crown angle that I was worried about; as i was seeing a reference range of approx 34-35. I was unsure as to how the pavilion angle and table would factor in with the larger crown angle. But if I get added fire, then I suppose that's no bad thing

 

[OoohShiny]

The usual Pricescope recommendations are for an HCA score of under 2 for a diamond within the following specs:

Table 54-58 %
Depth 60-62.4 %
Pavilion Angle 40.6-40.9 degrees
Crown Angle 34-35 Degrees (up to 35.5 with 40.6 pavilion)

but as you can see, HCA does show stones that have angles that work that are outside that range!


If you can get hold of an ASETscope, you can analyse how accurately cut the stone is - GIA rounds facet lengths / angles / etc., so you could have a wide range of angles making up an averaged single figure, which means you could have some leakage in one area but be fine in the rest.

I would agree that the stone sounds promising, though, and as you've seen it and liked it, that is a good thing

Just make sure to check it out in a range of lights, so not just the sparkly store lights, so you can see how bright it is and make sure it is reflecting from edge to edge (so looks as big as it is)!