Pearl Dreams
Pearl Enthusiast
- Joined
- Sep 24, 2007
- Messages
- 9,527
Have you ever wondered whether it's worth going up a size when buying pearls (or other round beads)?
Wondered whether the increased cost will be worth it-- and if you'll really be able to tell the difference?
The diameter of a pearl (its size in millimeters) doesn't tell the whole story and can be misleading when deciding what size pearls to buy.
What really matters is not the diameter, but the volume.
Why volume instead of diameter?
Pearls are 3 dimensional (not flat circles on a page as they are pictured)-- volume is all about the 3 dimensional size. How much space the pearl takes up! How large it looks.
Its visual impact.
And its weight.
Knowing the volume of a given pearl size lets you compare one size with another. It tells you how much larger (and heavier) any given pearl will be compared to another pearl.
You can also use this to estimate out how much larger and heavier a strand may be compared to another strand.
We do this by dividing the volume of the larger pearl by the volume of the smaller pearl (or in the case of strands, dividing volumes of the end pearls of the 2 strands and the center pearls of the 2 strands, and then averaging.)
I will demonstrate with examples below.
I've been having a little fun calculating volumes for different size round pearls.
Take this as a little guide to help you estimate how large a given size pearl is compared to another size pearl.
(Rounded off to the nearest whole number.)
16mm pearl: 2144 cubic mm (21% larger than 15mm pearls, and over 3 times as large as 11mm pearls.)
15mm pearl: 1766 cubic mm (23% larger than 14mm pearls)
14mm pearl: 1436 cubic mm (25% larger than 13mm) (twice as large as 11mm, and over 5x as large as 8mm pearls)
13mm pearl: 1150 cubic mm (27% larger than 12mm)
12mm pearl: 904 cubic mm (30% larger than 11mm and 73% larger than 10mm; over 3 times as large as 8mm)
11mm pearl: 697 cubic mm (33% larger than 10mm)
10mm pearl: 523 cubic mm (37% larger than 9mm, 95% larger than 8mm)
9mm pearl: 382 cubic mm (43% larger than 8mm; 2 times as large as 7mm pearls)
8mm pearl: 268 cubic mm (49% larger than 7mm)
7mm pearl: 180 cubic mm (59% larger than 6mm)
6mm pearl: 113 cubic mm (74% larger than 5mm pearls)
5mm pearl: 65 cubic mm
Note: An increase of one millimeter makes more of a difference when the pearls are small than when they are large. (This is because 1mm is a greater per cent of the total size of a small pearl than of a large pearl.)
You can do this calculation yourself for any pearl size (even half-sizes). All you need to know is the diameter.
Here's how, using a 7mm pearl as an example:
Volume (of a sphere) = 4/3 π (radius cubed)
• Divide the diameter in half to get the radius. (The radius of a 7mm pearl is 3.5)
• Multiply the radius by itself, and again by itself to get the radius cubed. (3.5 x 3.5 x 3.5 = 43, rounding it up)
• Then multiply the radius cubed by 3.14 (π, or "pi") (43 x 3.14 = 135)
• Now multiply that result by 4, and then divide by 3. (135 x 4 = 540, then divided by 3 = 180)
• The final result is the volume of that pearl in cubic millimeters, rounded off. (7mm pearl is approximately 180 cubic mm)
Alone, the volume is not very useful information, but it is very useful for comparing two pearl sizes so as to understand how much larger or smaller the pearls are.
To compare two pearl sizes, divide the volume of the larger pearl by that of the smaller pearl.
Example 1: How much larger is an 8mm pearl than a 7mm pearl?
Divide 268 cubic mm (volume of 8mm pearl) by 180 cubic mm (volume of 7mm pearl) = 1.49
Thus, 8mm pearls are 1.49 times as large as 7mm pearls, or stated differently, they are 49% larger by volume.
Another way to state this is that 8mm pearls will look about one and a half times as large as 7mm pearls-- and will weigh one and a half times as much.
Example 2: How much larger is a 10-12mm strand than a 9-11 mm strand?
A 12mm pearl is 30% larger than an 11mm pearl, so the center pearls in a 10-12mm strand will be 30% larger.
A 10mm pearl is 37% larger than a 9mm pearl, so the end pearls in a 10-12mm strand will be 37% larger.
I averaged 37% and 30% to get 33.5%.
Therefore a 10-12mm strand will be about a third larger overall (and a third heavier) than a 9-11mm strand.
A 12-14mm strand will be two-thirds (66%) larger than a 10-12mm strand.
And so on.
You can do this to compare any 2 strands, but it is just an estimate when it comes to strands, as some strands have a single, oversized center pearl, or only a few small pearls on the ends. Still it will give you an idea of relative size.
Going up by just a little can definitely impact appearance and weight.
If you are buying a rope, it's all the more important to consider the weight.
Wondered whether the increased cost will be worth it-- and if you'll really be able to tell the difference?
The diameter of a pearl (its size in millimeters) doesn't tell the whole story and can be misleading when deciding what size pearls to buy.
What really matters is not the diameter, but the volume.
Why volume instead of diameter?
Pearls are 3 dimensional (not flat circles on a page as they are pictured)-- volume is all about the 3 dimensional size. How much space the pearl takes up! How large it looks.
Its visual impact.
And its weight.
Knowing the volume of a given pearl size lets you compare one size with another. It tells you how much larger (and heavier) any given pearl will be compared to another pearl.
You can also use this to estimate out how much larger and heavier a strand may be compared to another strand.
We do this by dividing the volume of the larger pearl by the volume of the smaller pearl (or in the case of strands, dividing volumes of the end pearls of the 2 strands and the center pearls of the 2 strands, and then averaging.)
I will demonstrate with examples below.
I've been having a little fun calculating volumes for different size round pearls.
Take this as a little guide to help you estimate how large a given size pearl is compared to another size pearl.
(Rounded off to the nearest whole number.)
16mm pearl: 2144 cubic mm (21% larger than 15mm pearls, and over 3 times as large as 11mm pearls.)
15mm pearl: 1766 cubic mm (23% larger than 14mm pearls)
14mm pearl: 1436 cubic mm (25% larger than 13mm) (twice as large as 11mm, and over 5x as large as 8mm pearls)
13mm pearl: 1150 cubic mm (27% larger than 12mm)
12mm pearl: 904 cubic mm (30% larger than 11mm and 73% larger than 10mm; over 3 times as large as 8mm)
11mm pearl: 697 cubic mm (33% larger than 10mm)
10mm pearl: 523 cubic mm (37% larger than 9mm, 95% larger than 8mm)
9mm pearl: 382 cubic mm (43% larger than 8mm; 2 times as large as 7mm pearls)
8mm pearl: 268 cubic mm (49% larger than 7mm)
7mm pearl: 180 cubic mm (59% larger than 6mm)
6mm pearl: 113 cubic mm (74% larger than 5mm pearls)
5mm pearl: 65 cubic mm
Note: An increase of one millimeter makes more of a difference when the pearls are small than when they are large. (This is because 1mm is a greater per cent of the total size of a small pearl than of a large pearl.)
You can do this calculation yourself for any pearl size (even half-sizes). All you need to know is the diameter.
Here's how, using a 7mm pearl as an example:
Volume (of a sphere) = 4/3 π (radius cubed)
• Divide the diameter in half to get the radius. (The radius of a 7mm pearl is 3.5)
• Multiply the radius by itself, and again by itself to get the radius cubed. (3.5 x 3.5 x 3.5 = 43, rounding it up)
• Then multiply the radius cubed by 3.14 (π, or "pi") (43 x 3.14 = 135)
• Now multiply that result by 4, and then divide by 3. (135 x 4 = 540, then divided by 3 = 180)
• The final result is the volume of that pearl in cubic millimeters, rounded off. (7mm pearl is approximately 180 cubic mm)
Alone, the volume is not very useful information, but it is very useful for comparing two pearl sizes so as to understand how much larger or smaller the pearls are.
To compare two pearl sizes, divide the volume of the larger pearl by that of the smaller pearl.
Example 1: How much larger is an 8mm pearl than a 7mm pearl?
Divide 268 cubic mm (volume of 8mm pearl) by 180 cubic mm (volume of 7mm pearl) = 1.49
Thus, 8mm pearls are 1.49 times as large as 7mm pearls, or stated differently, they are 49% larger by volume.
Another way to state this is that 8mm pearls will look about one and a half times as large as 7mm pearls-- and will weigh one and a half times as much.
Example 2: How much larger is a 10-12mm strand than a 9-11 mm strand?
A 12mm pearl is 30% larger than an 11mm pearl, so the center pearls in a 10-12mm strand will be 30% larger.
A 10mm pearl is 37% larger than a 9mm pearl, so the end pearls in a 10-12mm strand will be 37% larger.
I averaged 37% and 30% to get 33.5%.
Therefore a 10-12mm strand will be about a third larger overall (and a third heavier) than a 9-11mm strand.
A 12-14mm strand will be two-thirds (66%) larger than a 10-12mm strand.
And so on.
You can do this to compare any 2 strands, but it is just an estimate when it comes to strands, as some strands have a single, oversized center pearl, or only a few small pearls on the ends. Still it will give you an idea of relative size.
Going up by just a little can definitely impact appearance and weight.
If you are buying a rope, it's all the more important to consider the weight.
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