高级
处理中...
Black Opal Brightness and Body Tone Guide
黑欧泊亮度和身体色调指南
此文本是机器翻译的。 显示原始图片?

处理中...

black opal brightness and body tone guideThe Opal Body Tone Guide was designed and created by the Opal Association of Australia and acts as a guide for Black Opal and Boulder Opals. The Opal industry has recently also been using this guide for many Opal types including Ethiopian Opals.

Body Tone N1 - N4 - Is for black tone body types.

Body Tone N5 - N7 - Is for light coloured Opals mined also at Lightning Ridge but these lower body tone grades can and have been used on Coober Pedy Opals and Ethiopian Opals.

Opal Brightness Guide

The Opal Brightness Guide assists in assigning a value to how bright an Opal is to the naked eye.

Brightest 1 to & Dullest 7 - Can be used on any Opal with 3.5 as average brightness for many opals considered commercial grade.

Brightness lower than a 3 - Is considered a B grade Opal or low Commercial grade.

How is Opal Color Produced?

Opal formation

The local name given potch, such as desert sandstone, is dependent upon the area in which they occur, but they all belong to the same families of felspathic sandstone, claystone, siltstone and mudstone, which are said to have been deposited over large areas buy streams and lakes.

We call any material that opal colour has formed on as Potch. Except for volcanic opal, which usually occurs in Tertiary rocks, all the types of opal we have come to know so well are found in these strata. Although the opal is found in the Cretaceous sediments, it is a matter of conjecture as to it’s deposition over millions of years during the Tertiary period. The general teaching is that certain minerals were broken down in the country rock to produce silica at 120 parts per million, and trace elements which were deposited in cavities left by bones, shells and other dissoluble material. These, as well as faults and fractures in the ground, provided pathways for the underground waters to carry the silica down at the end of the weathering period.

Although this is the entrenched theory, with “slight variations” depending on your source of information, it is fraught with problems which have been deleted from the model to give it credence. There is little doubt that all opal was not deposited in exactly the same manner. So far I have discovered four different ways in which it has been deposited; there may be more. They all have a common denominator in the equation, ionic-exchange. The fact is that opalization is extremely regional and that large beds of impervious barriers are only secondary to opal formation.

If the only requisite for opalization under the above model were suitable impervious traps, then there would be massive beds of opal over vast areas. However, as every opal miner knows, this is not the case and all opal is unpredictable and patchy in the extreme.

Australian Opal is rarely faceted, nearly always domed. A domed stone is stronger and less prone to chipping. However Opal without a play of color (such as cherry red or amber Opal from Mexico) is often faceted and can look a lot like ruby. Opals are a carver’s delight. The stone is not too hard to work with and will not wear out your diamond tools as much as such stones as Chrysoprase and Agate.

Opal Size

Popular sizes are listed below.

Round: 5 mm and 6 mm

Oval: 6 x 4, 7 x 5, 8 x 6, 9 x 7, 10 x 8, 12 x 10, 14 x 10, 16 x 12, 18 x 13, 20 x 15, 25 x 18, 30 x 22, 40 x 30.

Opal Settings

Jewellery castings for opals can range from very simple designs to very ornate designs with accent diamonds.

There are some interesting myths associated with Opal settings. Some folks believe that Opal Doublets and Triplets are always put into fully backed settings to hide the potch backing. Others believe that full backings are used to protect the stone. Neither myth is true. A jeweler could just as easily “hide” a doublet in an open backed setting, as the join line between the stone and the potch backing would be covered by the side of the setting, making it difficult to see whether the back of the stone was a different stone or simply the less brilliant side of the same stone.

How Opal is Graded and Sold

Rough Opal parcels are sorted into three grades: tops, middle, and low. Each tops parcel has a King stone, which is the best stone in the parcel. Some parcels have several King stones. Color is the primary criteria for grading, but the graders also take into consideration the number of imperfections and faults, and whether a stone is the right shape to be cut into an oval or one of the other popular shapes. You can buy rough opal in several different conditions.

Mine Run

Direct from the mine. The stones have not been cut or ground down. This means that there is more guesswork in the cutting. Purchasing mine run opal can be risky if you are not very experienced.

Off Cuts

The miner has removed whatever black opal rough ,he has a market for and sells you what’s left. With off cuts, you can usually tell what you are going to be able to cut. You must still watch for cracks in the opal because once a crack becomes obvious, a stone can lose half its value.

Rubs

This can often be the best way of buying black opal rough if you are not very experienced. The miner has cut and ground the stones into basic shapes, after having removed most of the rubbish. What you have left is the stone nearly ready for the dopping and polishing process. You have the satisfaction of cutting your own stones without the high risk of buying mine run rough.

Opal is officially sold in troy oz. There are approximately 30 grams to a troy oz and approximately 30-oz to a kilo.

Hints and Tips

Here’s an eclectic assortment of hints and tips you may find helpful when buying or working with opal.

1. Not all Opal is valuable. Potch, is sometimes called “common opal” does not reflect colors. Potch does have its use, however, as a backing for doublets and triplets. When there is color mixed with potch it’s called “potch and color.”

opal potch

2. Some classes of rough Opal are unsuitable for making gemstones. Some are very porous. Others have a chalky appearance. Still others can lose their color in a short period of time. And yes, it is common for certain types of opals to shatter in a dry atmosphere when the water from the gel evaporates. The best protection for buyers is to purchase opal from a knowledgeable and reputable dealer who accurately details exactly what you are purchasing and is willing to guarantee the stones. Note: If you buy rough opal, there is no guarantee that it will not crack. This is the calculated risk you take and is part of the “excitement” of opal cutting. opal potch

3. When examining opal jewellery, look at the stone from the side to determine whether it’s a triplet. Solid and doublet opal domes are simply the opals formed into a curved dome shape. Triplets have clear crystal domes to protect the flat opal surface.

4. It is very difficult to tell whether a stone is a doublet or a solid if it is in a setting. It helps if the back of the setting is open, but it is still no real indication because the back of a doublet and a solid looks very similar, although a doublet is usually perfectly black on the back whereas a solid black opal usually has some imperfections. So if the back of a stone looks too perfect, you have to be a little suspicious. For this reason it’s best to buy opal from reputable dealers who know what they are doing because, unfortunately, many jewelers also are not experienced in opal.

5. When buying opal over the net, ask the seller to give you a summary of how close the graphic sample is to the real thing. Opal is very difficult to photograph and the appearance on the computer screen may give it a different look. Particularly is this the case in regards to size. Graphics come out in all different sizes, usually a lot larger than actual…so make sure you get your ruler out and actually draw the size on a piece of paper so that you will know in your own mind’s eye the actual size of the stone.

6. The same thing applies to the color of the stone. Make sure you get the supplier to give a commentary on the color so that you will know pretty well what you are getting. The camera sometimes picks up colors that are only minimal, while ignoring the feature colors.

黑色蛋白石亮度和身体色调指南蛋白石体色调指南由澳大利亚蛋白石协会设计和创建,并作为Black OpalBoulder蛋白石的指南。蛋白石行业最近也将此指南用于许多蛋白石类型,包括埃塞俄比亚蛋白石

Body Tone N1 - N4 - 用于黑色调身体类型。

身体色调N5 - N7 - 适用于Lightning Ridge开采的浅色蛋白石,但这些较低的身体色调等级可用于Coober Pedy蛋白石和埃塞俄比亚蛋白石。

蛋白石亮度指南

蛋白石亮度指南有助于为肉眼看到蛋白石的亮度分配值。

最亮1至最低7 - 可用于任何蛋白石,平均亮度为3.5,适用于许多被视为商业级的蛋白石。

亮度低于3 - 被认为是B级蛋白石或低商业级。

蛋白石颜色是如何产生的?

蛋白石形成

当地的名称,如沙漠砂岩,取决于它们出现的区域,但它们都属于同一系列的长石砂岩,粘土岩,粉砂岩和泥岩,据说已经沉积在大面积上溪流和湖泊。

我们将任何以蛋白石颜色形成的材料称为Potch。除了通常发生在第三纪岩石中的火山蛋白石外,我们在这些地层中发现了我们所熟知的所有类型的蛋白石。尽管在白垩纪沉积物中发现了蛋白石,但在第三纪期间它的沉积数百万年是一个猜想。一般教学是在乡村岩石中分解某些矿物质以产生百万分之120的二氧化硅,以及沉积在由骨头,贝壳和其他可溶性物质留下的空腔中的微量元素。这些以及地下的断层和裂缝为地下水提供了在风化期结束时将二氧化硅带下来的通道。

虽然这是根深蒂固的理论,但根据您的信息来源有“微小的变化”,它充满了从模型中删除的问题以使其可信。毫无疑问,所有蛋白石都没有以完全相同的方式沉积。到目前为止,我已经发现了四种不同的沉积方式;可能会有更多。它们在等式中都有一个共同点,即离子交换。事实上,蛋白石化极具区域性,大型不透水屏障只是蛋白石形成的继发。

如果在上述模型下唯一的蛋白石化必要条件是适当的不透水陷阱,那么在广阔的区域将会有大量的蛋白石床。然而,正如每个蛋白石矿工都知道的那样,情况并非如此,所有蛋白石都是不可预测的,并且极端不完整。

澳大利亚蛋白石很少出现,几乎总是穹顶。圆顶石头更坚固,不易碎裂。然而,没有颜色的蛋白石(例如来自墨西哥的樱桃红或琥珀蛋白石)经常刻面,看起来很像红宝石。蛋白石是雕刻师的喜悦。石头不太难以使用,也不会像金石榴和玛瑙这样的石头磨损你的钻石工具。

蛋白石大小

热门尺寸如下。

圆形: 5毫米和6毫米

椭圆形: 6 x 4,7 x 5,8 x 6,9 x 7,10 x 8,12 x 10,14 x 10,16 x 12,18 x 13,20 x 15,25 x 18,30 x 22, 40 x 30。

蛋白石设置

蛋白石的珠宝铸件可以从非常简单的设计到非常华丽的设计与重点钻石。

Opal设置中有一些有趣的神话。有些人认为Opal Doublets和Triplets总是被置于完全支持的设置中以隐藏potch支持。其他人认为完全背衬用于保护石头。这两件事都不是真的。一个珠宝商可以很容易地“隐藏”在开放式背景中的双重线,因为石头和背景之间的连接线将被设置的一侧覆盖,使得很难看出石头的背面是否是不同的石头或简单的同一块石头的不太光亮的一面。

蛋白石如何分级和出售

粗糙的蛋白石包裹分为三个等级:顶部,中部和低部。每个上衣包裹都有一块King石头,这是包裹中最好的石头。有些包裹有几块King石头。颜色是分级的主要标准,但是分级者还要考虑缺陷和缺陷的数量,以及石头是否是切成椭圆形或其他流行形状的正确形状。您可以在几种不同的条件下购买粗蛋白石。

我的奔跑

直接从矿井。石头没有被切割或磨碎。这意味着切割中有更多的猜测。如果您不是很有经验,购买矿山蛋白石可能会有风险。

关闭

该矿工已经拆除了任何黑色蛋白石粗糙 ,他有一个市场,卖给你剩下的东西。通过剪切,您通常可以告诉您将要切割的内容。你仍然必须注意蛋白石的裂缝,因为一旦裂缝变得明显,石头就会失去一半的价值。

如果您不是很有经验,这通常是购买黑蛋白石粗糙的最佳方式。在清除了大部分垃圾后,矿工将石头切割成基本形状。你剩下的就是石头几乎准备好进行掺杂和抛光处理。你可以满足于削减自己的宝石,而不会有购买矿山粗糙的高风险。

蛋白石正式以特洛伊盎司出售。大约30克到金衡盎司,大约30盎司到一公斤。

提示和技巧

在购买或使用蛋白石时,您可能会发现这里有各种各样的提示和技巧。

并非所有蛋白石都有价值。 Potch,有时被称为“普通蛋白石”,不反映颜色。然而,Potch确实有它的用途,作为双头和三胞胎的支持。当有颜色与potch混合时,它被称为“potch and color”。

蛋白石potch

某些类粗糙蛋白石不适合制作宝石。有些非常多孔。其他人有白垩的外表。还有一些人可能会在短时间内失去颜色。是的,当凝胶中的水蒸发时,某些类型的蛋白石在干燥的环境中破碎是很常见的。对买家的最佳保护是从知识渊博且声誉良好的经销商那里购买蛋白石,该经销商准确地详细说明您的购买对象并愿意保证这些石头。注意:如果您购买粗糙蛋白石,则无法保证不会破裂。这是你冒的计算风险,也是蛋白石切割“兴奋”的一部分。 蛋白石potch

3.在检查蛋白石首饰时 ,从侧面看石头以确定它是否是三合一。实心和双层蛋白石圆顶简直就是形成弧形圆顶形状的蛋白石。三胞胎有透明的水晶圆顶,以保护平坦的蛋白石表面。

如果石头在一个环境中,很难判断一块石头是双峰还是实心。如果设置的背面是打开的,它仍有帮助,但它仍然没有真正的指示,因为双合透镜和实体的背面看起来非常相似,虽然背面的双合透镜通常是完全黑色,而实心的黑色蛋白石通常有一些缺陷。因此,如果石头的背面看起来太完美,你必须有点怀疑。出于这个原因,最好从信誉良好的经销商那里购买蛋白石,因为不幸的是,许多珠宝商也没有蛋白石经验。

5.通过网络购买蛋白石时,请卖方向您提供图形样本与真实物品的接近程度的摘要。蛋白石很难拍摄,而电脑屏幕上的外观可能会让它看起来不同。特别是在尺寸方面。图形以各种不同的尺寸出现,通常比实际尺寸大得多......所以一定要把尺子拿出来,然后在一张纸上画出尺寸,这样你就可以在自己的脑海中知道石头的实际尺寸。

6.同样的事情适用于石头的颜色。确保让供应商对颜色进行评论,以便您能够很好地了解您的情况。相机有时会拾取最小的颜色,同时忽略特征颜色。

此文本是机器翻译的。 显示原始图片?

本文是否有帮助?

38人们认为这篇文章很有帮助

注释

Opalplus

Over 5 years ago Opal buyers would constantly check and ask questions about Body tone for black opals.
Market trends have now changed, and most buyers ask about Brightness as well as Body tone.
Chinese buyers would only buy N1 body tone black opal and this placed a lot of demand for Body tone ahead of Brightness.
Today Brightness is the most important and has major consideration factor in valuing opals as well as the opal pattern.
Unfortunately we have two systems for Brightness ratings that have not been approved by Cibjo or leading gemmologist organizations.
On Opalauctions we recommend the Australian opal association Opal brightness Guide that places brightest opal at B1. compared to the original B5 rating.

29th Jan
Chasmalta

Yes I agree, Brightness should be included on black opal listing.

2nd Jan
Opalplus

Reply Tony translate
Or can we buy the rule Opal base body tone guide SVP
Yes here is link

https://www.opalauctions.com/auctions/two-body-tone-charts-599156

21st Jan 2017
Tony1966

Ou pouvons nous acheté la règle Opal base body tone guide SVP

21st Jan 2017
Opalmarket

Yes.Helped me a lot.Thank you.

3rd Oct 2016
Electra

I do get confused with body tone chart with brightness chart.
Its seems everyone states body tone of an opal but I think Brightness is just as important
Lot black opals now seem to be N2 to N3 as an average
I do not see many N1 black opals and they are all expensive now
That’s why I think Brightness is more important now and most are rated B3 to B4
May I make a suggestion that Brightness be added below Body tone on black opal listings

24th Aug 2016
A-Z Of Opals

A-Z Of Opals

A complete list of your favourite Opal from all over the world
19文章
Did you know?

Did you know?

Check out our fascinating information and articles on all things amazing in the Opal world
36文章
How To's

How To's

All of your favourite Opal How To's
18文章
News

News

What's trending in the Opal Industry
40文章
Opal Auctions  Verified Sellers

Opal Auctions Verified Sellers

Opal Auctions sellers who are approved as opal Verified Sellers
4文章
Opal Information

Opal Information

Information about Opal and its colorful history
100文章
Opal Stories

Opal Stories

Feel like reading a yarn or two?
6文章
Technical Opal Information

Technical Opal Information

All there is to know about Opals including Black Opals, Ethiopian Opals & Boulder Opal
14文章
Testimonials

Testimonials

Feedback from our VIP customers
5文章