What Is The Difference With Crazing to Crack In An Opal?

加工...

Many opal cutters will sell stones that have cracks or crazing in their opals. There is a major difference between the two and we will show you what it is. While there is nothing wrong with buying an Opal that is crazed or cracked it is important that the buyer is made aware before the purchase. If your Opal does have fracture lines in it or it has crazed do not put it in an ultrasonic cleaner as it may destroy the Opal.

CRACKS

A crack can be a minor or major fault line. It can be on the surface or internal. If you see a line inside the opal and it reflects light then it is a crack in the stone. External cracks will decrease the value / price more than internal cracks.

Internal cracks have been shown to be stable and not continue to grow. Some Opal miners have stones with cracks inside them that have had no movement. External crack lines in a polished opal can be cut out but obviously this decreases the size and value of the Opal.

Cracked opals do not necessarily mean that they will fall apart. Many cracked opals will hold but the biggest problem is if an opal is cracked and in a ring, the everyday wear and tear and knocks will break the Opal. Many cracked opals are set as pendants for this reason and are able to be worn most of the time.

CRAZING

Crazing looks like multiple crack lines. Crazed opal is mostly kept as specimens or collectors pieces. They are not recommended for use in Jewelry. Crazed opals can be treated with Opticon which stabilises the Opal.

The image above is an Ethopian Opal with an inclusion. Notice there is no light reflection.

Inclusions are not cracks. Many opals contain natural inclusions. These can be air bubbles, vegetation matter and even potch.

AUSTRALIAN OPAL

Most Australian opal is very stable with black opal [N1] considered the most stable due to its smaller molecules. Generally Australian Opal that displays a crack is set at 10-20% of the value of a stable opal of similar qualities. It is estimated only around 1-3% of Australian opals crack but some opal fields are more susceptible than others.

Most Australian Opals contain 3-5% water. Generally the deeper the miner digs the more water content the Opal will have. Mines at Lighting Ridge go down to about 30 meters and the miner can gauge how stable the Opal is. As the potch goes from tough dry material to soggy wet potch then it is an indication of stable material. When they go deeper and the miner knows that this opal will obviously have more water content.

Most Australian opals are non porous and therefore they do not absorb water.

POTCH LINES

Some opals may show veins or spider web lines. These are not cracks but potch lines. It is easy for the cutter to check as crack lines reflect light but potch lines do not. Potch lines do decrease the value of the opal depending on the severity of lines. They do not generally effect the stability of the opal.

ETHIOPIAN OPAL

Ethiopian opal is a Hydrophane opal. Hydrophane opal absorbs water. When Ethiopian opal is dehydrated the base is more opaque. when the opal is hydrated it becomes more transparent. Transition time from hydrated to dehydrated can vary from minutes to days but most Opals do transition in a few hours.

FRACTURE TESTING ETHIOPIAN OPAL

Gemstones have been fractured or cleavage tested for centuries to test parting or cleavage in rough material. All major carving or cutting centres fracture test material before cutting or carving.

Even before modern testing techniques were invented rough material was still tested. During winter a wood fire would warm up a room and cold water was splashed repeatedly on the rough.

Today this basic process is still used for opals by soaking the opals in water and drying them in a warm but not hot environment. This processes can be repeated several times before the cutting process starts. Some opal with a small crack line will sometimes expand under water.

This process tests the stress points and cracks will appear on the weakest cleavage point. The opal is now ready for cutting and polishing to remove any visible cracks.

Fractures or crazing and cracks can appear as:

granular sugary patterns
smooth even breaks
rough edged irregular breaks

Cutters obviously make decision to cut an opal after it has been fractured tested as to observe which side of the opal the fracture occurs on. This involves great skill and a professional cutter will cut according to the directions that have opened up when the fracture is complete.

It takes a cutter many years of experience to understand the best approach to cutting an opal. Master opal cutters will charge a percentage cutting fee for top stones from 3 to 5% and in most cases this is worth paying!

OPTICON STABILIZATION

Opticon is the most common form for stabilising opal. Immerse the stones in a canning style jar filled with enough Opticon to cover the stones and tighten the lid so water can not escape. Condensation can turn the resin cloudy.

Place the jar in a ordinary slow cooker filled with enough water so the jar dose not float.
Turn the heat up to 150-170 degrees Celsius (302 - 338 Fahrenheit)
use a thermometer to check the temperature. We recommend using a kitchen meat thermometer.
Cook for 24 hours
Strain off the excess resin and place on tinfoil

Use a vacuum machine like the ones used to vacuum food bags. This sucks the air out of the bag.

Vacuum for at least one hour.
Using an artist style brush paint the stone with a weak mixture [40 to 1] of resin and hardener and re vacuum for 15 minutes.
Remove any excess moisture with a acetone cloth.
When the stones are no longer tacky polish or re-polish

This 54.7 carat Harlequin pattern opal was sold for over $1,100. When it was cut 5 years ago it displayed crazed lines. The owner treated the stone with Opticon and sold it for around 10% of its value if it was untreated.

GLUES

You can also coat the stone with super glue and heat it under strong lights. The glass like covering over the stone gives it stability while it is polished.

BOULDER OPAL

Boulder opal is mostly formed on an ironstone backing and is stable. This ironstone can be A deep brown chocolate color to sandy ironstone with a light brown colour. Ironstone does help to keep the opal stable. Some crack lines may appear at a 45% degree angel but the opal can still be stable. Some boulder crystal opal may also display cracks. Koroit and Yowah opal fields are considered stable.

MEXICAN OPAL

Most Mexican opal is stable. Crazed or cracked opals can occur when the potch and opal cut in one piece as each has different pressure threshold.

U.S.A. OPALS

USA Opals are generally not considered to be stable and opals are mostly made in to Triplets or stabilised. USA opals tend to craze as water content can go up to 14%

BRAZILIAN OPALS

These are generally considered stable as the water content is mostly less than 5%. The opals are semi translucent to white translucent.

HONDURAN OPAL

Honduras opal on matrix is considered stable but some crystal formed on matrix may display crack lines

Browse Our Opals

Black Opal

Boulder Opal

Crystal Opal

Ethiopian Opal

許多蛋白石切割商會出售蛋白石上有裂縫或裂紋的寶石。兩者之間存在重大差異，我們將向您展示它是什麼。雖然購買發瘋或破裂的蛋白石沒有任何問題，但在購買前讓買家了解這一點很重要。如果您的蛋白石確實有斷裂線或已經開裂，請勿將其放入超聲波清潔器中，因為它可能會損壞蛋白石。

裂紋

裂縫可以是次要或主要斷層線。它可以在表面或內部。如果您看到蛋白石內部有一條線並且它反射光，那麼它就是石頭上的裂縫。外部裂縫比內部裂縫更能降低價值/價格。

內部裂紋已被證明是穩定的，不會繼續擴大。一些蛋白石礦工的石頭內部有裂縫，這些石頭沒有移動。拋光蛋白石的外部裂紋線可以被切掉，但這顯然會降低蛋白石的尺寸和價值。

破裂的蛋白石並不一定意味著它們會分崩離析。許多破裂的蛋白石會保持，但最大的問題是如果蛋白石破裂並且在戒指中，日常磨損和敲擊會破壞蛋白石。由於這個原因，許多破裂的蛋白石被設置為吊墜，並且大部分時間都可以佩戴。

瘋狂

裂紋看起來像多條裂紋線。瘋狂蛋白石大多作為標本或收藏品保存。不建議將它們用於珠寶。瘋狂的蛋白石可以用穩定蛋白石的 Opticon 處理。

上圖是一顆含有內含物的埃塞俄比亞蛋白石。注意沒有光反射。

夾雜物不是裂紋。許多蛋白石含有天然內含物。這些可能是氣泡、植被物質甚至是potch。

澳大利亞蛋白石

大多數澳大利亞蛋白石非常穩定，黑蛋白石 [N1] 因其較小的分子而被認為是最穩定的。通常，顯示出裂紋的澳大利亞蛋白石的價值是類似品質的穩定蛋白石的 10-20%。據估計，只有大約 1-3% 的澳大利亞蛋白石破裂，但一些蛋白石領域比其他領域更容易受到影響。

大多數澳大利亞蛋白石含有 3-5% 的水。一般來說，礦工挖得越深，蛋白石的含水量就越多。 Lighting Ridge 的礦井下降到大約 30 米，礦工可以測量蛋白石的穩定性。當鍋具從堅硬的干燥材料變為濕濕的鍋具時，它表明材料穩定。當他們深入時，礦工知道這塊蛋白石顯然會含有更多的水分。

大多數澳大利亞蛋白石是無孔的，因此它們不吸水。

POTCH LINE

一些蛋白石可能會出現靜脈或蜘蛛網線。這些不是裂縫，而是坑洼線。切割機很容易檢查，因為裂紋線會反射光，而鍋槽線不會。斑點紋確實會根據紋路的嚴重程度降低蛋白石的價值。它們通常不會影響蛋白石的穩定性。

埃塞俄比亞蛋白石

埃塞俄比亞蛋白石是一種Hydrophane蛋白石。親水蛋白石吸收水分。當埃塞俄比亞蛋白石脫水時，底部會變得更不透明。當蛋白石水合後，它會變得更加透明。從含水到脫水的過渡時間可以從幾分鐘到幾天不等，但大多數蛋白石會在幾個小時內過渡。

斷裂測試埃塞俄比亞蛋白石

幾個世紀以來，寶石一直在進行斷裂或解理測試，以測試粗糙材料的分離或解理。所有主要雕刻或切割中心在切割或雕刻前測試材料斷裂。

甚至在現代測試技術發明之前，仍會測試粗糙材料。在冬天，木火會溫暖一個房間，冷水反复潑在粗糙的地方。

今天，這個基本過程仍然用於蛋白石，將蛋白石浸泡在水中，然後在溫暖但不熱的環境中乾燥。在切割過程開始之前，此過程可以重複多次。一些帶有小裂紋線的蛋白石有時會在水下膨脹。

這個過程測試應力點，裂紋會出現在最弱的解理點上。蛋白石現在可以進行切割和拋光，以去除任何可見的裂縫。

裂縫或裂紋和裂紋可能表現為：

顆粒狀含糖圖案
平滑甚至斷裂
毛邊不規則斷裂

切割者顯然會在蛋白石經過斷裂測試後決定切割它，以觀察斷裂發生在蛋白石的哪一側。這需要很高的技巧，專業的切割器會根據骨折完成後打開的方向進行切割。

切割師需要多年的經驗才能了解切割蛋白石的最佳方法。頂級蛋白石切割師將收取 3% 至 5% 的百分比切割費，在大多數情況下，這是值得支付的！

光學穩定器

Opticon 是穩定蛋白石的最常見形式。將石頭浸入裝有足夠 Opticon 的罐頭式罐子中，以蓋住石頭並擰緊蓋子，以免水溢出。冷凝會使樹脂變混濁。

把罐子放在一個普通的慢燉鍋裡，裡面裝滿了足夠的水，這樣罐子就不會漂浮了。
將溫度調高至 150-170 攝氏度（302 - 338 華氏度）
使用溫度計檢查溫度。我們建議使用廚房肉類溫度計。
煮24小時
濾去多餘的樹脂，放在錫紙上

使用真空機，如用於真空食品袋的真空機。這會將空氣從袋子中吸出。

抽真空至少一小時。
使用藝術家風格的刷子用樹脂和硬化劑的弱混合物 [40 比 1] 在石頭上塗漆，然後再抽真空 15 分鐘。
用丙酮布除去多餘的水分。
當寶石不再發粘或重新拋光時

這顆 54.7 克拉的丑角圖案蛋白石售價超過 1,100 美元。當它在 5 年前被切割時，它顯示出瘋狂的線條。所有者用 Opticon 處理了這塊石頭，如果未經處理，則以大約 10% 的價格出售。

膠水

您也可以在石頭上塗上強力膠並在強光下加熱。石頭上的玻璃狀覆蓋物使其在拋光時具有穩定性。

博爾德蛋白石

博爾德蛋白石主要形成在鐵石背襯上並且很穩定。這種鐵石可以是深棕色的巧克力色，也可以是淺棕色的砂質鐵石。鐵石確實有助於保持蛋白石的穩定。一些裂紋線可能會以 45% 的角度出現，但蛋白石仍然可以保持穩定。一些巨石水晶蛋白石也可能出現裂縫。 Koroit 和 Yowah 蛋白石領域被認為是穩定的。

墨西哥蛋白石

大多數墨西哥蛋白石是穩定的。當potch和蛋白石切割成一塊時，可能會出現裂紋或破裂的蛋白石，因為它們各自具有不同的壓力閾值。

美國蛋白石

美國蛋白石通常不被認為是穩定的，蛋白石大多製成三胞胎或穩定的。美國蛋白石趨於熱潮，因為含水量可高達 14%

巴西蛋白石

這些通常被認為是穩定的，因為水含量大多低於 5%。蛋白石是半透明至白色半透明。

洪都拉斯蛋白石

基質上的洪都拉斯蛋白石被認為是穩定的，但基質上形成的一些晶體可能會顯示裂紋線

加工... What Is The Difference With Crazing to Crack In An Opal? 蛋白石開裂與開裂有什麼區別？ 該文本是機器翻譯的。 顯示原件？