Gemological Characteristic Difference between Colorless CVD Synthetic Diamonds and Natural Diamonds

Abstract

CVD synthetic diamond plays an important role in the jewelry market due to its excellent performance and low cost. In this paper, colorless CVD synthetic diamonds produced by a Chinese company were investigated in detail with their gemological, spectroscopic, and luminescent properties compared with natural colorless diamonds. Compared with natural diamonds, CVD synthetic diamonds have high-order interference color and more apparent abnormal birefringence. The results of infrared spectra indicate that all the CVD samples are classified as type IIa, while the natural samples belong to type Ia. The CVD samples show lamellar growth and mottled luminescence pattern and have blue, orange red, purple red, and blue fluorescence, respectively, while most of the natural samples show blue fluorescence. CVD diamonds show lamellar growth structure, and natural diamonds show irregular ring-like growth structure. Thus, multiple methods combined with analysis are required to distinguish synthetic diamonds from natural diamonds. This work provides an experimental basis for the identification of CVD synthetic diamonds.

Color Centers in Hexagonal Boron Nitride

“…Single-crystal diamonds have a 5.47 eV bandgap, making them transparent in the visible wavelength range. However, occasionally, natural and artificial diamonds show various colors of luminescence depending on their natural vacancies or extrinsic impurities in the crystal lattice under ultraviolet excitation, as shown in Figure 2 a [ 14 ]. Due to this phenomenon, optically active atomic defects are known as “color centers” in ultrawide-bandgap materials.…”

“… ( a ) Fabricated colored diamonds of various colors with luminescent characteristics. The colors were observed using ultraviolet fluorescence (265 nm) using DiamondView (De Beers, London, UK) [ 14 ]. ( b ) Types of color centers: vacancy, substitutional, interstitial, and self-interstitial color centers [ 15 ].…”

“…In this paper, we compiled data from recent research papers published between the years 2016 and 2023 ([ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ,…”

“… A survey of hBN color center emission wavelengths. ( a ) ZPL wavelength of color centers in the hBN distribution [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , …”

Untitled

“…For example, the following markets could be pointed out (THL, 2021): The Chinese jewelry market is of characteristic worth that began with ancient crafts and the most exquisite works made by the hands of those craftsmen. Mainly due to the fact that, although contemporary research is being conducted in the field of shaping goldsmith products and the uniqueness of the materials used in this craft (See: Zhou et al, 2021;Lu et al, 2021;Lu et al, 2015), nevertheless, "(...) in the field of processing precious metals, antiquity has already done everything that could be done, and later times could at most certainly add to it some technical improvements that would shorten the path to the goal a bit" (Gradowski, 1980, p. 15).…”