The region was evidently rather sparsely inhabited by
several groups of Indigenes when Columbus visited in 1502.
The "Indians" worked gold, which of course piqued the
interest of the intrepid entrepreneur, but they were well
armed and resisted attempts at colonization until the
regular army came in 1530.  There had not been a lot of
Indians on the rich coast to begin with, and the smallpox
brought by the Spaniards did a job on the rest.  As a result
the country today is the most Europeanized in Central
America.
Eventually the land was incorporated in the
Captaincy-General of Guatemala.  Coins in use during the
colonial period would have been the usual mix of Spanish
silver and gold, mainly of Mexico, Potosi, Guatemala, and
Nueva Reino.  No coins were struck in San Jose until the
Central American Republic period.  "CR" marked coins of the
CAR are scarcer, by and large, than the Guatemala issues.
Politically the CAR was a dead letter from the
beginning, though it was not formally dissolved until 1848.
The states were essentially independent throughout, though
coins continued to be struck in the name of the Union until
the end.
FIRST COINS
The first coins for Costa Rica proper were the holed
and countermarked coins of 1841-42.  This is not a
particularly common countermark, and even the 2 reales coins
with the low SCWC prices are hard to find, those that do
show up are usually quite the worse for wear.  These were
was succeeded by the 1845 counterstamps, examples of which
can be found fairly easily.  The 1845 validation was used
only on 2 reales coins, and if you find it on another
denomination you're almost certainly looking at a fake.
In 1842 a silver ½ real and gold escudo were struck at
San Jose.  The silver is very scarce.  The gold is very
rare.
Another set of countermarks was used in 1846 employing
the familiar CAR types of "Sun over Mountains" and "Tree of
Liberty."  The "1 R" type was used on 1 real cobs, which are
common, and also, with an additional "4" mark, on 4 reales,
which are scarce.  It is known on half dollars of the USA,
and these have been extensively faked.  A "2 R" version was
used on 2 reales cobs, which again are fairly common, and on
a smattering of other 2 bits coins, which are rare and
subject to forgery.  This countermark with additional "8"
mark on 8 reales cobs is rare.
I real silver coins were struck in 1847.  These are
common as worn pieces.  High grades are very tough.
The third countermark series of 1849-50 was originally
applied only on ½, 1, and 2 reales size coins, and on small
gold of the CAR.  The dies were used again in 1857 on
British sixpence and shillings,   It is common on silver,
rare on gold.  Unfortunately the dies are still extant and
people have been creating fakes of all denominations,
including 4 and 8 reales struck on coins of the USA.
Silver 1 real coins struck in 1849 and 1850 are common.
The gold series begun in 1850 is, of course, scarcer,
through the ½ and 1 escudos show up in F-VF from time to
time.  Also starting in 1850 the government experimented
with fractional peso denominations.  These coins are hard to
find.  When, after years of search I finally stumbled upon a
set of 1850 1/16, 1/8, and 1/4 pesos, all in crummy
condition, they were snapped up instantly.  It's not often
you get multiple orders for beat up coins with holes in
them.
DECIMALS
The first decimal series was inaugurated in 1864 with
two types of silver 25¢ and a little gold peso.  The silver
pieces are not easy to find, the gold is scarce.  These were
followed a year later by a full range of minor coins
including the ¼ centavo and 1¢ in newfangled copper nickel.
These base metal coins are hard to find, especially the
scarce-to-rare ¼¢.  The alloy did not hold up well in the
tropical climate, and corrosion spots and pitted surfaces
are the rule.  Silver "tree" coins are not common,
especially the 50¢, and were circulated to a fare-thee-well.
Average grade these days is fair-good, and the only common
date is 1865, though "common" is probably the wrong word.
The tree was abandoned as a silver type after 1875,
replaced by the arms of the nation.  Here we first run into
one of the peculiarities of Costa Rica coinage, which is the
notoriously shallow engraving of the shield.  This has been
a feature of the coinage since the type was adopted.
Frequently the shield will look most of a grade lower than
the rest of the coin.  I believe one should try to stick by
the international grading traditions, where a slick
escutcheon makes a coin a maximum of VG, but in a series
like Costa Rica this makes for a giant pool of low grade
coins, a few in XF-AU-Unc, and very few in F-VF.  On the
earliest dates of the silver shield coins low grades are the
rule and the coins themselves are not so common.  1890 and
'92 coins, except for the 50¢, can be found in high grades
at reasonable prices.  Gold coins of this series are not
particularly common, circulated versions of the 1 and 2
pesos are most occasionally seen.
Coin shortage in 1889 necessitated the importation of
Colombian 50¢ coins, which were thereupon counterstamped.
These coins are reasonably common as types in grades of fine
and under.  I've heard, but cannot confirm, that the dies
still exist in private hands.  Any coin with this
counterstamp other than a Colombian 50¢ is a fantasy.
TWENTIETH CENTURY
The first colon types were the gold "Columbus" coins of
1897.  As old gold goes they are fairly common, especially
the little 2 colones of 1900.  They are usually found in XF
or better.
(Gold is so hard to grade at the top.  Consumer Reports
did an article on slabs.  One USA $20 piece was submitted
numerous times and came back "officially" graded in a nice
range from AU-58 to MS-64!)
In this first colon series the silver 5 and 10¢
(centimos) are common in high grades, with a decent
population available in strict uncirculated for all dates.
The 50¢ coins are quite a bit scarcer, as most were
counterstamped in 1923.  1914 date without counterstamp is a
celebrated rarity.
The 2¢ coin in copper-nickel is common, despite a large
number having been turned into 5¢ pieces in 1942.
Uncirculated specimens without problems are scarce.
From 1917 through 1919 the minor unit was styled
"centavo."  Aside from that the types remained the same.
The silver 10¢ is not common, despite its low catalog price.
Having been replaced almost immediately by a brass version,
the coin disappeared from circulation.  Compared with 1910
coins, for instance, it is scarce.  The brass coins are
common enough in good-very good.  Uncirculated coins are
very scarce, without spots they are rare.  The 50¢ coins of
1917-18 are basically unknown without the 1923 countermark.
Supposedly only 10 of the 1917s and none of the 1918s missed
the revaluation.  I suppose someone knows where each of
those 1917 coins are.
In 1920 they changed the minor denomination back to
"centimos," beginning the modern series which continues
today.  To my mind the series divides up into three periods
based on denomination set and metal content.  In the early
period, 1920-29, brass and bronze were used one 5 and 10¢
and silver for the top value 25¢.  1935 marked the
introduction of a 50¢ and 1 colon in copper-nickel.  The
copper-nickel period, broken occasionally by emissions in
stainless steel and brass, and once by bronze, ended in
1979.  1980 saw the start of debasement, with higher values
and aluminum coins coming into use.
All first period coins can be found.  Average grade is
G-VG (mostly because of the escutcheon).  Top grades are
hard to find.  The 5¢ of 1920 and 1921 are relatively
scarce.  The silver 25¢ of 1924 is a common coin (except in
Unc).  Unfortunately, it seems that one of the major dealers
in Costa Rica cleaned a lot of silver coins at one time, and
many of these are found that way.
Not all copper-nickel period coins can be found.  1935
coins are no problem.  They even occur in Unc.  Coins from
1936 through 1947 are all available, though tough in Unc.
Exception is the 1942 5¢ in copper-nickel.  It's often crude
and you can usually clearly see the 2¢ design underneath,
but it does turn up in Unc.  Coins of 1948 through the end
of the sixties are very common and no problem in Unc.
This is also true for coins of the seventies for the
most part.  The exceptions are for those years where there
are two different types of arms for a given coin in a given
year.  Some of these coins never turn up.  The ones I've
never come across are the "small ships" 5¢ of 1976 and '78,
"large ships" 10¢ of 1976, "large ships" 25¢ of 1976, '77,
and '78, and my records show I've never had the 1970 and '74
either.  Could these be rare?  In 50¢ the tough one is the
small date 1975.  In 1 colons it's the large ships varieties
of 1976-78.  There had been large and small ships varieties
listed in older versions of the SCWC for the 2 colones of
1961.  The large ships variety has been dropped from the
current edition.  I guess no one ever saw one.
All of the base metal coins from 1979 are very common
and cheap.  Stainless steel inflation coins of 5, 10, and 20
colones tend to come in XF-AU rather than Unc.
COMMEMORATIVES
Commemorative coins began issue in 1970 with a set of
gold and silver proof coins.  The silver proof set is
moderately available, gold a bit less so.  1974 gold and
silver Conservation coins are readily available.  The silver
pieces are among the more common of that series.  1975
"Central Bank" coins are rarely found in Unc, let alone in
proof.  The Year of the Child coin with the little birds is
common as well.  The 1981 coins don't seem very common to
me, nor the Franklin Mint issues of 1982 and '83.  The 1987
Oscar Arias coins are available.
PATTERNS & TOKENS
There are a few patterns known.  The only ones which
exist in quantity are the 19xx 5 and 10¢ (of 1929).  I've
had one of these, and the story that came with it was that
there was one roll known of each, dispersed in the
mid-sixties.
Costa Rica has a large series of tokens made from the
nineteenth century through the 1960s.  It is probably the
largest token series in Central America.  Many of the common
ones will go for $3.00 or less.