Encycolorpedia

CIL Starry Night / #6b9dc2 Hex Color Code

#6b9dc2 Paint ChipThe hexadecimal color code #6b9dc2 is a shade of cyan-blue. In the RGB color model #6b9dc2 is comprised of 41.96% red, 61.57% green and 76.08% blue. In the HSL color space #6b9dc2 has a hue of 206° (degrees), 42% saturation and 59% lightness. This color has an approximate wavelength of 480.81 nm.

Buy Paint Buy paint matching this color

Stock Photos / Images / Pictures

Save 10% on premium images with code ISTOCK10.

  1. Ferry boat in front of Perito Moreno glacier, blue ice burg glacier from peak of the mountain through the blue lake in Los Glaciares National Park, Santa Cruz, Argentina, southern Patagonia ice field
  2. jeans background XXXL
  3. Lake rural

Color Variations

Related Named Colors

Color Schemes

Download: GIMP GPL Adobe ASE (Adobe Swatch Exchange) Sketch Palette

#6b9dc2 linear gradient to complementary #b79976

  1. #6b9dc2
  2. #7e9cb5
  3. #8d9ca9
  4. #999b9c
  5. #a49a90
  6. #ae9a83
  7. #b79976

Monochromatic Colors

  1. #4d81a4
  2. #578aae
  3. #6193b8
  4. #6b9dc2
  5. #75a7cc
  6. #7fb1d6
  7. #89bae1

Tones

  1. #6b9dc2
  2. #759cbb
  3. #7d9bb4
  4. #849aac
  5. #8b99a5
  6. #91989e
  7. #979797

Tints and Shades

#6b9dc2 to white

  1. #6b9dc2
  2. #85adcc
  3. #9ebdd6
  4. #b7cde0
  5. #cfddeb
  6. #e7eef5
  7. #ffffff / #fff

#6b9dc2 to black

  1. #6b9dc2
  2. #59819f
  3. #48667d
  4. #374c5c
  5. #27343e
  6. #181d22
  7. #000000 / #000

Paints

Exact Matching Paints

Similar Paints

  1. Earthpaint

    1. ★ 2-35-4 Versailles
      #6d9dc2
      ΔE = 0.369 / LRV ≈ 31.3%
    2. 3-36-4 Blue Emotion
      #7899b6
      ΔE = 3.019 / LRV ≈ 30.2%
  2. TRUMATCH

    1. ★ 32-d4
      #6e9ec2
      ΔE = 0.558 / LRV ≈ 31.7%
    2. 31-d5
      #6a98b8
      ΔE = 2.347 / LRV ≈ 29.0%
  3. Opaltone / OMS

    1. ★ 6107
      #6b9bbf
      ΔE = 0.757 / LRV ≈ 30.3%
    2. 6114
      #6493ba
      ΔE = 3.758 / LRV ≈ 27.1%
  4. Clark+Kensington

    1. ★ Rhythm and Blues / 36C-5
      #679cc0
      ΔE = 0.945 / LRV ≈ 30.5%
  5. Devoe Paint

    1. ★ Harbor Blue / 22BB 34/304
      #6b9fc7
      ΔE = 1.157 / LRV ≈ 32.0%
    2. ★ Starry Night / 10BB 32/262
      #6c9dbc
      ΔE = 2.063 / LRV ≈ 30.9%
  6. General Paint

    1. ★ Maltese / CL 2315D
      #6d9fc7
      ΔE = 1.327 / LRV ≈ 32.2%
    2. Thesus / CL 2254D
      #679ebd
      ΔE = 2.764 / LRV ≈ 31.0%
  7. Asian Paints

    1. ★ Firmament / 7343
      #6699c0
      ΔE = 1.632 / LRV ≈ 29.4%
    2. Calming Blue / 9200
      #799cb9
      ΔE = 2.692 / LRV ≈ 31.3%
  8. Glidden

    1. ★ Blue Promise / PPG1161-4
      #729cc2
      ΔE = 1.685 / LRV ≈ 31.2%
    2. Gingham Blue / 10BB 30/203
      #7796b8
      ΔE = 3.670 / LRV ≈ 29.2%
  9. Bristol

    1. ★ Blueberry Slice / P111-C4
      #759ec2
      ΔE = 1.698 / LRV ≈ 32.1%
    2. Regatta / P109-C4
      #69a2d1
      ΔE = 3.459 / LRV ≈ 33.4%
  10. Nerolac

    1. ★ Blue Winks - 4265
      #6499c0
      ΔE = 1.704 / LRV ≈ 29.3%
    2. Spa - 4273
      #4e9ac4
      ΔE = 3.832 / LRV ≈ 28.7%
  11. Apple Barrel

    1. ★ Sky Blue / 20770
      #6ba1c4
      ΔE = 1.783 / LRV ≈ 32.6%
  12. Valspar Paint

    1. ★ Bluestone
      #739abb
      ΔE = 1.856 / LRV ≈ 30.3%
    2. Blue Marble R171C
      #8399b7
      ΔE = 4.874 / LRV ≈ 31.0%
  13. Pantone / PMS

    1. ★ 542
      #6699c2
      ΔE = 1.970 / LRV ≈ 29.5%
    2. 645
      #7d99ba
      ΔE = 3.804 / LRV ≈ 30.7%
  14. ICI Paints

    1. ★ Bristol 10BB 37/234
      #73a2c4
      ΔE = 2.140 / LRV ≈ 33.5%
    2. Arctic Flow 90BG 33/249
      #609dbc
      ΔE = 3.639 / LRV ≈ 30.2%
  15. Berger

    1. ★ Birds egg blue / 7343
      #6198c0
      ΔE = 2.233 / LRV ≈ 28.8%
    2. Postcard Perfect / 7295
      #6e91b3
      ΔE = 4.557 / LRV ≈ 26.8%
  16. Scib Paints

    1. ★ Birds egg blue / 7343
      #6198c0
      ΔE = 2.233 / LRV ≈ 28.8%
    2. Bonaventure / 7359
      #4a9cc7
      ΔE = 4.139 / LRV ≈ 29.4%
  17. Vista Paint

    1. ★ Bird's Egg Blue
      #6198c0
      ΔE = 2.233 / LRV ≈ 28.8%
    2. Far Horizons
      #86a4c2
      ΔE = 4.838 / LRV ≈ 35.5%
  18. GM / General Motors

    1. Nassau Blue
      #769fbd
      ΔE = 2.324 / LRV ≈ 32.3%
    2. Marietta Blue
      #7096bb
      ΔE = 3.035 / LRV ≈ 28.8%
  19. Behr

    1. Blue Bell RAH-79
      #709dba
      ΔE = 2.477 / LRV ≈ 31.1%
    2. Cornflower P520-4
      #6aa0d0
      ΔE = 3.652 / LRV ≈ 32.8%
  20. Natural Color System / NCS

    1. S 2030-R90B
      #759abf
      ΔE = 2.490 / LRV ≈ 30.7%
    2. S 2030-B
      #6ca2c1
      ΔE = 3.056 / LRV ≈ 32.9%
  21. Peintures MF

    1. Bleu divin
      #5e9ac6
      ΔE = 2.492 / LRV ≈ 29.6%
    2. CD336-4
      #7fa2be
      ΔE = 3.768 / LRV ≈ 34.1%
  22. FolkArt

    1. Blue Echo / 2639
      #7197b7
      ΔE = 2.629 / LRV ≈ 29.1%
    2. Skyline / 2499
      #559cbe
      ΔE = 4.257 / LRV ≈ 29.4%
  23. Games Workshop - Citadel

    1. Fenrisian Grey
      #719bb7
      ΔE = 2.747 / LRV ≈ 30.4%
    2. Chronus Blue
      #72a8d1
      ΔE = 4.168 / LRV ≈ 36.2%
  24. California Paints

    1. DE 5850 - Wandering River
      #73a4c6
      ΔE = 2.777 / LRV ≈ 34.3%
    2. DE 5857 - Blue Agave
      #65a5d5
      ΔE = 4.115 / LRV ≈ 34.5%
  25. Kelly-Moore

    1. Bird's Egg Blue / KM3142-2
      #73a4c6
      ΔE = 2.777 / LRV ≈ 34.3%
    2. Piece of the Sky / KM3125-2
      #7b99b4
      ΔE = 3.603 / LRV ≈ 30.3%
  26. Evonik-Degussa

    1. 5214T Brewster Blue
      #7b9cbb
      ΔE = 2.782 / LRV ≈ 31.6%
    2. 7222T Fresco Blue
      #7aa6ca
      ΔE = 3.758 / LRV ≈ 35.7%
  27. Tollens

    1. T2012-5
      #6e97b5
      ΔE = 2.870 / LRV ≈ 28.8%
    2. T2010-5
      #6a97c4
      ΔE = 3.813 / LRV ≈ 29.2%
  28. Pratt & Lambert

    1. Celestrial 26-10
      #6ea5cb
      ΔE = 2.877 / LRV ≈ 34.5%
    2. Paradise Lost 26-12
      #5494c4
      ΔE = 4.917 / LRV ≈ 27.0%
  29. Brillux

    1. 63.15.18
      #6fa5ca
      ΔE = 2.891 / LRV ≈ 34.6%
    2. 60.15.18
      #7a9cc5
      ΔE = 3.964 / LRV ≈ 31.9%
  30. CIL

    1. Tibet Blue
      #7498b5
      ΔE = 2.920 / LRV ≈ 29.5%
    2. Periwinkle Blue
      #7c9ec3
      ΔE = 3.280 / LRV ≈ 32.7%
  31. Toyo Ink

    1. CF10690
      #749ab5
      ΔE = 3.061 / LRV ≈ 30.2%
    2. CF10446
      #80a0ca
      ΔE = 5.046 / LRV ≈ 34.0%
  32. KILZ

    1. Nantucket Shore / C751
      #7ba3c4
      ΔE = 3.103 / LRV ≈ 34.4%
    2. Lake Periwinkle / B891
      #7d9dc5
      ΔE = 4.201 / LRV ≈ 32.5%
  33. Ford

    1. Medium Blue Diamond Bright
      #7c9ec2
      ΔE = 3.117 / LRV ≈ 32.6%
    2. Miami Blue
      #6c9fce
      ΔE = 3.469 / LRV ≈ 32.4%
  34. Diamond Vogel

    1. Key West Zenith / 0646
      #7da2c2
      ΔE = 3.203 / LRV ≈ 34.1%
    2. Heavenly Sky / 0618
      #7393b4
      ΔE = 4.170 / LRV ≈ 27.8%
  35. Sikkens

    1. S6.27.56
      #6ea4c4
      ΔE = 3.249 / LRV ≈ 33.8%
    2. S1.26.51
      #6597b0
      ΔE = 5.100 / LRV ≈ 28.0%
  36. 1829

    1. Medium Persian Blue
      #6f9cc9
      ΔE = 3.318 / LRV ≈ 31.4%
  37. Dutch Boy

    1. Summer Fun Blue
      #69a3c3
      ΔE = 3.339 / LRV ≈ 33.1%
    2. Agile Blue
      #5a9ec0
      ΔE = 3.674 / LRV ≈ 30.4%
  38. Plascon

    1. Quiet Peace B3-D2-2
      #7c9cc0
      ΔE = 3.342 / LRV ≈ 31.9%
    2. Serene Setting B3-C2-2
      #78a4cc
      ΔE = 3.513 / LRV ≈ 34.9%
  39. Resene

    1. Snap B70-088-235
      #5ba0d0
      ΔE = 3.348 / LRV ≈ 31.9%
    2. Shakespeare B67-062-229
      #609ab8
      ΔE = 3.883 / LRV ≈ 29.1%
  40. RAL

    1. RAL 250 60 25
      #5d96b9
      ΔE = 3.432 / LRV ≈ 27.6%
    2. RAL 250 60 20
      #6a95b1
      ΔE = 3.972 / LRV ≈ 27.7%
  41. Crown Diamond

    1. 7330-42 Half-moon
      #7da2bf
      ΔE = 3.446 / LRV ≈ 34.0%
    2. 7327-42 Crystal Ware
      #7ca3ce
      ΔE = 4.614 / LRV ≈ 34.9%
  42. Taubmans

    1. Regatta / T12 40.E3
      #69a2d1
      ΔE = 3.459 / LRV ≈ 33.4%
    2. Inca Blue / T64-5
      #839eb9
      ΔE = 4.201 / LRV ≈ 32.8%
  43. Laura Ashley

    1. 1404 Chambray 4
      #6095b7
      ΔE = 3.519 / LRV ≈ 27.4%
    2. 44-15 Foxglove Blue
      #84a2c6
      ΔE = 4.729 / LRV ≈ 34.8%
  44. Levis

    1. Clear Blue C50
      #5c9bcc
      ΔE = 3.636 / LRV ≈ 30.1%
    2. Mild Indigo
      #7e9db2
      ΔE = 4.827 / LRV ≈ 31.8%
  45. Volkswagen

    1. Florida Blue
      #7fa3c4
      ΔE = 3.640 / LRV ≈ 34.7%
    2. Miami Blue
      #5693bb
      ΔE = 4.416 / LRV ≈ 26.4%
  46. Sherwin-Williams

    1. Jacaranda - 6802
      #5a9ec0
      ΔE = 3.674 / LRV ≈ 30.4%
    2. Bluebird Feather - 9062
      #6f9db3
      ΔE = 5.162 / LRV ≈ 30.7%
  47. Disney

    1. 3C-30-3 Oh Bother Blue
      #7ca5c5
      ΔE = 3.705 / LRV ≈ 35.2%
    2. P5-2 Eeyore's Blues
      #879eba
      ΔE = 4.923 / LRV ≈ 33.1%
  48. Little Greene

    1. Lagoon
      #78a3cd
      ΔE = 3.767 / LRV ≈ 34.6%
  49. Porter Paints

    1. Alaskan Blue / 348-4
      #7d9dc3
      ΔE = 3.777 / LRV ≈ 32.4%
    2. Serene Sea / 350-4
      #77a6c3
      ΔE = 4.227 / LRV ≈ 35.1%
  50. New Look

    1. Andys Fan / E22-04
      #7299b2
      ΔE = 3.799 / LRV ≈ 29.6%
    2. Twiddle Dum / E22-10
      #76a4c0
      ΔE = 3.896 / LRV ≈ 34.2%
  51. Albany Paint

    1. Kentucky Blue
      #63a2d3
      ΔE = 3.801 / LRV ≈ 33.2%
  52. Para

    1. Blue Dazzle / 208E
      #6d93b7
      ΔE = 3.819 / LRV ≈ 27.5%
  53. Federal Standard

    1. Federal Standard 35240
      #7f9cbf
      ΔE = 3.852 / LRV ≈ 32.0%
    2. Federal Standard 25240
      #7f99bb
      ΔE = 4.322 / LRV ≈ 30.9%
  54. Sto

    1. 35110
      #6695c1
      ΔE = 3.883 / LRV ≈ 28.2%
    2. 35221
      #7fa6c0
      ΔE = 4.911 / LRV ≈ 35.6%
  55. Man

    1. Guineablau / LH5K
      #5f9ab8
      ΔE = 4.023 / LRV ≈ 29.0%
  56. Cloverdale Paint

    1. Birds Egg Blue / 7343
      #64a1bf
      ΔE = 4.025 / LRV ≈ 32.0%
    2. Breathtaking Blue / 7327
      #58a5d7
      ΔE = 4.624 / LRV ≈ 33.9%
  57. Loop

    1. Monpellier / LP-215
      #7c97b4
      ΔE = 4.035 / LRV ≈ 29.7%
    2. Nantes / LP-210
      #77a5bf
      ΔE = 4.663 / LRV ≈ 34.6%
  58. Focoltone

    1. 2198
      #6a9cb6
      ΔE = 4.079 / LRV ≈ 30.2%
    2. 1060
      #7091b8
      ΔE = 5.154 / LRV ≈ 27.2%
  59. Caran d'Ache

    1. 662 Genuine Cobalt Blue
      #63a2d4
      ΔE = 4.082 / LRV ≈ 33.2%
    2. 755 Gray Blue
      #5ea7d9
      ΔE = 4.957 / LRV ≈ 35.0%
  60. Dulux

    1. Mediterranean Blue / 30BB 27/236
      #6c92b4
      ΔE = 4.090 / LRV ≈ 27.0%
    2. 90BG 29/267
      #579ab9
      ΔE = 4.827 / LRV ≈ 28.6%
  61. Dunn-Edwards

    1. Marina / 337
      #65a5d5
      ΔE = 4.115 / LRV ≈ 34.5%
    2. Downpour / 577
      #819ab1
      ΔE = 4.724 / LRV ≈ 31.0%
  62. Chrysler

    1. Robin Egg Blue
      #7d98ba
      ΔE = 4.156 / LRV ≈ 30.4%
    2. Light Blue
      #7692ae
      ΔE = 4.905 / LRV ≈ 27.5%
  63. Colortrend

    1. 0618
      #7393b4
      ΔE = 4.170 / LRV ≈ 27.8%
    2. 0589
      #8297b6
      ΔE = 5.209 / LRV ≈ 30.3%
  64. ECOS Paints

    1. Heavenly Sky (0618)
      #7393b4
      ΔE = 4.170 / LRV ≈ 27.8%
    2. Celestial Horizon (0589)
      #8297b6
      ΔE = 5.209 / LRV ≈ 30.3%
  65. Ressource Peintures

    1. Jewel Blue / VINT02
      #5fa5d6
      ΔE = 4.303 / LRV ≈ 34.2%
    2. Della Robbia Blue / HC108
      #7d99c0
      ΔE = 4.696 / LRV ≈ 30.9%
  66. Caparol

    1. Iris 15
      #68a8cc
      ΔE = 4.313 / LRV ≈ 35.3%
    2. 41/07
      #5ca8d8
      ΔE = 4.937 / LRV ≈ 35.2%
  67. British Standard

    1. BS 4800 20 E 51 - Cornflower blue / Corfu
      #6fa5d4
      ΔE = 4.333 / LRV ≈ 35.0%
  68. Brighto Paints

    1. 2010 Blue Flame
      #5d9dd1
      ΔE = 4.377 / LRV ≈ 31.0%
    2. 3-33-5 Sea Breeze
      #62a0bd
      ΔE = 4.437 / LRV ≈ 31.4%
  69. Olympic

    1. Boudoir Blue A51-4
      #79a8cf
      ΔE = 4.428 / LRV ≈ 36.6%
    2. Salute B52-3
      #7ea9c7
      ΔE = 5.106 / LRV ≈ 36.9%
  70. Krylon

    1. Peekaboo Blue
      #83a1c5
      ΔE = 4.507 / LRV ≈ 34.3%
  71. Vallejo Game Color

    1. Ice Blue (095)
      #6b9cce
      ΔE = 4.534 / LRV ≈ 31.4%
  72. Old Citadel

    1. Ice Blue
      #6b9cce
      ΔE = 4.534 / LRV ≈ 31.4%
  73. Rackham

    1. Glacier Blue (9)
      #6b9cce
      ΔE = 4.534 / LRV ≈ 31.4%
  74. Vallejo Model Color

    1. Azure (902)
      #6b9cce
      ΔE = 4.534 / LRV ≈ 31.4%
  75. Duron

    1. Leisure Blue
      #6d91b5
      ΔE = 4.584 / LRV ≈ 26.8%
  76. Sigma

    1. Cool Blue / FS098
      #6b9fb8
      ΔE = 4.646 / LRV ≈ 31.4%
    2. Cool Blue / S 3040-R90B
      #5b91b6
      ΔE = 4.753 / LRV ≈ 25.9%
  77. Nippon Paint

    1. Cottage Blue / NP PB 1511 T
      #869eba
      ΔE = 4.718 / LRV ≈ 33.1%
    2. Blue Emotion / NP PB 1518 T
      #7ba1ce
      ΔE = 4.875 / LRV ≈ 34.2%
  78. Jedynka

    1. Pd 1101
      #809fb5
      ΔE = 4.720 / LRV ≈ 32.7%
  79. Matthews Paint

    1. Blue Nose / 7455
      #7993b3
      ΔE = 4.874 / LRV ≈ 28.2%
  80. Coronado Paint

    1. 7327 - Breathtaking Blue
      #4c9dd2
      ΔE = 4.897 / LRV ≈ 30.3%
    2. 7295 - Postcard Perfect
      #6990ae
      ΔE = 5.026 / LRV ≈ 26.0%
  81. Benjamin Moore

    1. Lake Tahoe / 783
      #4399c5
      ΔE = 4.948 / LRV ≈ 28.0%
    2. Sailor's Sea Blue / 2063-40
      #4b94bf
      ΔE = 5.030 / LRV ≈ 26.4%
  82. Tikkurila

    1. 2107
      #7792af
      ΔE = 4.948 / LRV ≈ 27.6%
  83. Abet Laminati

    1. Blu Zaffiro 484
      #6894c3
      ΔE = 5.035 / LRV ≈ 28.1%
  84. Mylands of London

    1. Wedgewood
      #879ebe
      ΔE = 5.096 / LRV ≈ 33.3%
  85. PPG Pittsburgh Paints

    1. American Anthem / PPG1156-4
      #7595ab
      ΔE = 5.107 / LRV ≈ 28.2%
    2. Society Street Chs-34
      #7a98ac
      ΔE = 5.241 / LRV ≈ 29.6%
  86. Johnstone's Paint

    1. Blue Star
      #4d99ce
      ΔE = 5.162 / LRV ≈ 28.8%
  87. Teknos

    1. GBI079
      #7da3b9
      ΔE = 5.207 / LRV ≈ 34.1%
    2. GBI048
      #869eb4
      ΔE = 5.210 / LRV ≈ 32.8%

Color Blindness Simulation

Monochromacy

Dichromacy

Trichromacy

#6b9dc2 HTML / CSS Code Examples

#6b9dc2 foreground

Nature is not only all that is visible to the eye.. it also includes the inner pictures of the soul.

Edvard Munch
<p style="color: #6b9dc2">…</p>

#6b9dc2 background

I wish they would only take me as I am.

Vincent Van Gogh
<p style="background-color: #6b9dc2">…</p>

#6b9dc2 shadow

A great artist is always before his time or behind it.

George Moore
<p style="text-shadow: 0.1em 0.1em 0.15em #6b9dc2">…</p>

Color Charts

Color Space Conversions

Decimal
7052738
Binary
01101011, 10011101, 11000010
Hexadecimal
#6b9dc2
LRV
≈ 31.1%
Closest short hex
#69b ΔE = 2.008
RGB
rgb(107, 157, 194)
RGBA
rgba(107, 157, 194, 1.0)
rg chromaticity
r: 0.234, g: 0.343, b: 0.424
RYB
red: 41.961%, yellow: 54.412%, blue: 76.078%
Android / android.graphics.Color
-9724478 / 0xff6b9dc2
HSL
hsl(206, 42%, 59%)
HSLA
hsla(206, 42%, 59%, 1.0)
HSV / HSB
hue: 206° (205.517), saturation: 45% (0.448), value: 76% (0.761)
HSP
hue: 205.517, saturation: 44.845%, perceived brightness: 58.407%
HSLuv (HUSL)
H: 236.704, S: 57.303, L: 62.620
Cubehelix
H: -159.309, S: 0.503, L: 0.573
TSL
T: -2.069, S: 0.134, L: 0.574
CMYK
cyan: 45% (0.448), magenta: 19% (0.191), yellow: 0% (0.000), key: 24% (0.239)
CMY
cyan: 58% (0.580), magenta: 38% (0.384), yellow: 24% (0.239)
XYZ
X: 27.855, Y: 31.133, Z: 55.570
xyY
x: 0.243, y: 0.272, Y: 31.133
CIELab
L: 62.620, a: -6.762, b: -24.278
CIELuv
L: 62.620, u: -23.951, v: -36.467
CIELCH / LCHab
L: 62.620, C: 25.202, H: 254.437
CIELUV / LCHuv
L: 62.620, C: 43.629, H: 236.704
Hunter-Lab
L: 55.797, a: -8.535, b: -19.991
CIECAM02
J: 51.864, C: 36.251, h: 238.000, Q: 141.887, M: 31.701, s: 47.268, H: 300.220
OSA-UCS
lightness: -10.190, jaune: -4.147, green: 2.471
LMS
L: 24.762, M: 33.589, S: 55.154
YCbCr
Y: 141.639, Cb: 151.643, Cr: 103.423
YCoCg
Y: 153.750, Cg: 3.250, Co: 5.000
YDbDr
Y: 146.268, Db: 71.821, Dr: 74.679
YPbPr
Y: 149.014, Pb: 24.250, Pr: -26.702
xvYCC
Y: 143.977, Cb: 149.302, Cr: 104.544
YIQ
Y: 146.268, I: -41.673, Q: 0.939
YUV
Y: 146.268, U: 23.490, V: -34.450
Munsell Color System
2.5PB 6/6 ΔE = 2.248
Brand Color
Foursquare ΔE = 6.514

Random Colors

Red

Green

Blue