Table:
0
A
B
C
D
E
F
1
Month
15th- 20th century
U.S. (1912)
U.S. (2013)
Britain (2013)
Hindu
2
January
garnet
garnet
garnet
garnet
serpent stone
3
February
amethyst , hyacinth , pearl
amethyst
amethyst
amethyst
chandrakanta
4
March
heliotrope , jasper
heliotrope , aquamarine
aquamarine , heliotrope
aquamarine , heliotrope
Gold Siva-linga
5
April
diamond , sapphire
diamond
diamond
diamond , rock crystal
diamond
6
May
emerald , agate
emerald
emerald
emerald , chrysoprase
emerald
7
June
cat's eye , turquoise , agate
pearl , moonstone
pearl , moonstone , alexandrite
pearl , moonstone
pearl
8
July
turquoise , onyx
ruby
ruby
ruby , carnelian
sapphire
9
August
sardonyx , carnelian , moonstone , topaz
sardonyx , peridot
peridot
peridot , sardonyx
ruby
10
September
chrysolite
sapphire
sapphire
sapphire , lapis lazuli
zircon
11
October
opal , aquamarine
opal , tourmaline
opal , tourmaline
opal
coral
12
November
topaz , pearl
topaz
topaz , citrine
topaz , citrine
cat's-eye
13
December
heliotrope , ruby
turquoise , lapis lazuli
turquoise , zircon , tanzanite
tanzanite , turquoise
topaz

Questions and formulas:
Question: What was Britain's (2013) birthstone when the U.S (2013) birthstone was ruby?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,D1="ruby"),5))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F13,D2:D13="ruby"),5))
Level: medium
Question: What was the U.S birthstone in 1912 when in 2013 the birthstone was amethyst?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,D1="amethyst"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F13,D2:D13="amethyst"),3))
Level: medium
Question: What was the U.S birthstone in the 15th-20th century when in 2013 it was amethyst?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,D1="amethyst"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F13,D2:D13="amethyst"),2))
Level: medium
Question: Which month in 2013 did the U.S. use the ruby birthstone?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,D1="ruby"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F13,D2:D13="ruby"),1))
Level: medium
Question: In 1912 when the U.S used sapphire, what was the Hindu birthstone?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,C1="sapphire"),6))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F13,C2:C13="sapphire"),6))
Level: medium