China, 17^th to 18^th century. Of rectangular form, finely carved and reticulated with a central rectangular plaque framed by two confronting kui dragons to the top and two phoenixes to the bottom, their faces neatly incised with almond-shaped eyes. The opaque stone of creamy ivory tone with red alterations, pale celadon areas, and extensive veining.

Provenance: British trade.
Condition: Very good condition with minor wear, few small nicks and minuscule nibbling to exposed areas, the stone with natural fissures.

Weight: 55.6 g
Dimensions: Length 6.4 cm

Chicken bone is a term for a rare and highly coveted nephrite jade of an opaque creamy beige color, often with extensive dark veining, which was particularly valued between the later Ming and early Qing dynasties. It is also sometimes said to be ‘burnt jade’, which has an opaque chalky appearance, usually with minute cracks all over the surface. It is known that nephrite – when heated to about 1000 degrees Celsius in a dry atmosphere – breaks down into diopside, enstatite (a magnesium silicate) and some quartz. In an experiment in the Freer Gallery Laboratory, samples of blue-green and white nephrite were submitted to temperatures up to 1025 degrees Celsius, and both altered to an opaque chalky beige color with no change in the shape of the piece or the decoration of the surface. The chief mineral which resulted was diopside, and several nephrite jades in the Freer which appear to have been burnt also give a diopside x-ray diffraction pattern. Jadeite, when heated in a similar manner, behaves quite differently: it fuses to a glassy material, the surface smoothens out, and if the object is small enough, it bends out of shape. See Elisabeth West, Jade: Its Character and Occurrence, The Bulletin of the University Museum of Pennsylvania, Volume 5, Issue 2, Winter 1963, page 5.

Auction result comparison:
Type: Related
Auction: Christie’s London, 17 May 2013, lot 1445
Price: GBP 2,500 or approx. EUR 3,900 converted and adjusted for inflation at the time of writing
Description: A ‘chicken-bone’ jade ‘landscape’ plaque, 17th/18th century
Expert remark: Compare the similar material and color. Note the slightly larger size (8.2 cm).



明末清初雞骨白夔龍玉牌
中國，十七至十八世紀。長方形，鏤空雕刻，上方兩條相對的夔龍，下面兩隻鳳凰。象牙色的不透明玉料，帶有紅色、淺青色紋理。

來源：英國古玩交易。
品相：狀況極好，有輕微磨損，輕微小刻痕和刻痕，玉料有天然裂縫。

重量：55.6 克
尺寸：長6.4 厘米

雞骨白是一種稀有的軟玉，呈不透明的乳白色，通常帶有廣泛的深色脈紋，在明末清初尤其受到重視。它具有不透明的鈣化斑，通常表面有微小的裂縫。眾所周知，軟玉在乾燥大氣中加熱到約 1000 攝氏度時會分解成透輝石、頑火輝石（一種矽酸鎂）和一些石英。在 Freer Gallery 實驗室的一項實驗中，藍綠色和白色軟玉樣品被置於高達 1025 攝氏度的溫度時，兩者都變成了不透明的白堊色，但其形狀或表面裝飾沒有變化 . 產生的主要礦物是透輝石，Freer Gallery中的幾種軟玉似乎已經燒過，也給出了透輝石 X 射線衍射圖。翡翠以類似的方式加熱時表現完全不同。有關雞骨白請參見 Elisabeth West，Jade: Its Character and Occurrence，賓夕法尼亞大學博物館公報，第 5 卷，第 2 期，1963 年冬季，第 5 頁。

拍賣結果比較：
形制：相近
拍賣：倫敦佳士得，2013年5月17日，lot 1445
價格：GBP 2,500（相當於今日EUR 3,900）
描述：十七/十八世紀雞骨白山水玉牌
專家評論：比較相似的材料和顏色。請注意slightly 尺寸較大(8.2 厘米)。