• Economic and Environmental Geology
• /
• v.26 no.1
• /
• pp.107-114
• /
• 1993

For the blue sapphires from Santung, China, the color change before and after has been investigated by UV-Visible spectrophotometry method. The blue sapphires from Shantung show four groups of absorption bands: the bands A (374, 386 and 450 nm) being attributed to single $Fe^{3+}$ ion, the band B (560, 579 and $704n{\breve{m}}$) to $Fe^{2+}$/$Ti^{4+}$ pairs, the band C (-800 nm) to $Fe^{2+}$/$Fe^{3+}$ pairs, and the D (528 nm) to $Ti^{3+}$ dd transitions. From those UV-VIS characteristics the origin of blue color of the sapphires is confirmed to be attributed by the factors such as $Fe^{2+}$/$Fe^{3+}$ and $Ti^{3+}$/$Ti^{4+}$. The absorption spectra of natural blue sapphires before and after heat treatment show distintive features, comparing with those of sapphires from other localities: the bands of 689 nm and of $Cr^{3+}$ are not recorded on the spectra of sapphires from Shantung. The band (492 nm), which resulted from $Ti^{3+}$, is not shown and the intensity of the band 528 nm decreases after the heat treatment. Decoloration of ink-blue sapphires are found to be successful by heat treatment with the control of annealing and atmosphere. During the diffusion process the excess components of impurities contained originally in the host crystal were expelled to the surface of crystals, enhancing the transparency of the crystals noticeably.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.4 no.1
• /
• pp.17-21
• /
• 2003

It has been difficult to characterize the value of treated sapphires for gem stones with bare eyes. Color enhancing treatments by diffusion and annealing became sophisticated and customers and gemologists had asked a non-destructive and fast characterization method. We suggest that Fourier transformation infra-red (FTIR) offers to characterize the cobalt-doped synthetic sapphires successfully in 3 minutes. Our results imply that FTIR may be employed in jewelry business to identify the treated sapphires in quantitative way.

• Journal of the Korean Ceramic Society
• /
• v.52 no.2
• /
• pp.165-170
• /
• 2015

We employed the high-pressure high temperature (HPHT) process to enhance the colors of natural sapphires to obtain a vivid blue. First, we analyze the content of the coloring agent $Fe_2O_3$ using the wavelength dispersive X-ray fluorescence (WD-XRF) method. The HPHT procedure operates under 1 GPa at various temperatures of 1700, 1750, and $1800^{\circ}C$ for 5 minutes using a cubic press. We determine the color changes using the optical microscopic images, UV-VIS near-infrared (NIR) spectra, micro-Raman spectra, and Fourier transform-infrared (FT-IR) spectra for all sapphire samples before and after the treatment. The optical microscopic results indicate that the HPHT process can enhance the sapphire color to a vivid blue at temperatures above $1750^{\circ}C$. The UV-VIS-NIR spectra identify the color changes explicitly and quantitatively through providing the Lab color scales and color differences. Both results demonstrate that the colors of natural sapphires can be enhanced to a vivid blue using the HPHT process above $1750^{\circ}C$ under 1 GPa for 5 minutes.

• Journal of the Korean institute of surface engineering
• /
• v.38 no.2
• /
• pp.83-87
• /
• 2005

We enhanced the color of blue sapphires and rubies successfully by using a oxygen-propane torch flame annealing, which had not been employed so far. We confirmed that about 1 mm-thick de-coloring of the corundum samples were available with 60 minutes flame annealing through eye evaluation, color coordination characterization, and methylene iodide immersion observation. We also suggest that the color centers such as $[Fe_{Al}^{\cdot}]$ may transform into transparent $[Fe_{Al}^{x}],\;[Cr_{A1}^{x}]$ sites with $[V_o^']$ generation at the elevated temperature in oxygen-rich atmosphere by diffusion mechanism. Our results implied that the longer diffusion time and the higher oxygen partial pressure might lead to the better de-coloring enhancement in corundum gem stones.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.6 no.2
• /
• pp.105-109
• /
• 2005

We heat treated pure sapphire samples at $1800^{\circ}C{\sim}100$ hours in BeO-${Al_2}{O_3}$ powder by varying BeO contents of $5{\sim}50\;wt%$ in order to quantify the BeO diffusion enhancement for corundum gem stones. We investigated the heat treated samples with visual evaluation, color coordination analysis, and surface roughness measurement. We confirmed that $Be^{2+}$ ions did not lead to orange color but to dark gray. The lightness in CIE Lab index decreased while surface roughness increased rapidly as BeO contents increased. We propose that BeO yellow color enhancement may be feasible only for $Fe^{3+}$ rich blue sapphires and sub-5% BeO content be appropriate to shorten post re- cutting process.

• International Journal of Precision Engineering and Manufacturing
• /
• v.7 no.4
• /
• pp.14-17
• /
• 2006

A thin GaN semiconducting film that grows on sapphires due to metalorganic chemical vapor deposition was machined for nanophotonic applications. The thin film had multilayered superlattice structures, including nanoscaled InGaN layers. Eight alternating InGaN/GaN multilayers provided a blue light emission source. Nanoscaled holes, 150 nm in diameter, were patterned on polymethylmethacrylate (PMMA) film using an electron beam lithography system. The PMMA film blocked the etching species. Air holes, 75 nm in diameter, which acted as blue light diffraction sources, were etched on the top GaN layer by an inductively coupled plasma etcher. Hexagonal lattice photonic crystals were fabricated with 230-, 460-, 690-, and 920-nm pitches. The 450-nm wavelength blue light provided the nanodiffraction destructive and constructive interferences phenomena, which were dependent on the pitch of the holes.

• The Research Journal of the Costume Culture
• /
• v.26 no.5
• /
• pp.793-805
• /
• 2018

At the beginning of the $20^{th}$ century, Cartier developed Art Deco jewelry designs that have been used as design inspirations to this day. The purpose of this study is to analyze the characteristics of the Art Deco jewelry designs of Cartier in the early $20^{th}$ century. Regarding the research method, this study explored the jewelry designs from 1904 to 1939 by extracting 288 analysis subjects from Cartier's exhibitions, auction picture books, and foreign books, and analyzed the characteristics in terms of design motifs, colors and materials. The results of the study are as follows. Regarding the design motifs, 73% were geometric motifs, and 66% were a combination of circular shapes and polygons, the most frequent. In terms of colors, 69% were chromatic in color, and vivid colors were mostly used in the order of red (24%), - green (19%), and - blue (14%). Of the materials, 92% of the metals consisted of platinum, and gemstones were used in the order of diamonds (41%), - onyx (13%), - emeralds (11%), - rubies (9%), and - sapphires (8%). In the early $20^{th}$ century, Cartier's Art Deco jewelry designs featured abstract and geometric motifs, vivid colors and strong contrasts, platinum and precious gemstones. This study is meaningful in that it explores the competitiveness of Cartier's designs and provides practical ideas to combine Art Deco style with contemporary jewelry designs successfully.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.3 no.1
• /
• pp.1-11
• /
• 1979

This is a study on angels' costumes in religious paintings, especially as this relates to the questions of concepts and theological symbolism. Angels, as spiritual creatures in Christian thought, play the role of praising God's glory, as messengers of God, the role of guarding Israel and the Church, and protecting or punishing human beings. Sometimes the angels appear in incarnate form. They display no sexual differences and are not able to procreate. The angels' funtional classification being thus; nevertheless, they are pictured in various costumes and appearances according to characteristics of the paintings. The angel Michael appears as a man of dignity when pictured as a guard; the angel Gabriel in the annunciation is often portrayed as a woman of mystical beauty. Under the Renaissance, the mighty cherubim and seraphim at Yahweh's throne are degraded as plump child-angels, or winged child-heads looking alike Eros or Cupid. They have become playful and all too obviously non-heavenly chrubs, accepted features of the Temple decorations. However, cherubim are often depicted as naked or wrapped around with a piece of cloth and accompanied with wind, which symbolizes the Glory of God. The angels, costumes without seam are hung over or wrapped around the body, and when sewn they are simple and ample enough that they fall in a great many folds. However, by the 14C. angels are mostly dressed in costumes common to all Europe, and after that angels gradually appear in folk costumes; for example Italian, Flemish, etc. Dalmatic, the typical costume of Byzantine often shows up as angels' dresses even after the period. Originally the dalmatic was the Roman tunic to which Eastern influences added. The Roman clavus on the tunic had gradually lost distinction until, by the Imperial epoch, it was worn by the lowest servants. It was proudly therefore, as 'The servants of God', that the early Christians are shown wearing the clavus on their wide, ungirdled, sleeved dalmatics. In addition to their costume, angels have some other distinct charateristics. First, angels have a halo around their head; this symbolizes their holiness. Second, angels wear a narrow diadem or a queen's crown that seems to denote their glorious status close to God's throne. Third, the cloth band across the breast resembles a priest's stole, which suggests the sacred role of a priest and symbolizes the grace santified. Fourth, lilies in the annunciations are symbols of Mary's virginity. chastity, innocence and heavenly bliss. Angels hold palms or olives in their hands. The former denote prosperity. beauty and the Christians' reward after death; the latter represent peace and amity. the imperial crown made of olives means victory. Fifth, angels in paintings always have a pair of wings, which can be traced to scripture where cherubim and seraphim are described as having pairs of wings. Angels' wings often have colors of the rainbow, and the rainbow is compared to God's glory. Sixth, generally artists paint angels' costumes as white, blue, green, gold and purple. Other colors such as red rarely appear. According, to scriptures it is believed that angels should be depicted 'as white as snow'. According to the biblical expressions of angels as lightning, sun or a pillar of fire, angels should be described as creatures of light. Nevertheless being a form of art, religious paintings may differ in their presentation according to an artist's inspiration and intention. Since religious paintings illustrated above were almost all done before the Reformation, symbols of colors used in the Catholic Church will also be mentioned. The white color symbolizes chastity, purity, brightness, delight and divinity. Green represents new birth, eternal life, spiritual revival and the expectance of the grace of God. Blue, the color of sapphires, denotes chastity and truth. Red, the color of rubies, represents divinity, love and religious passion. Violet is the color of dignity, indicating the sovereign, royal or imperial power and the great Sacrifice of Christ. As mentionad above, angels' costumes were expressed in accordance with contemporary patterns or as indicated in the Bible, and accesories and colors correspond with Christian symbols. Therefore these facts should be taken into consideration when it comes to the study of costume history.