Blisters and color change:
A Chazazis and a color change in the Esrog receive the following laws:
What is defined as a color change:
Admur brings different types of color changes:
Apparent at first sight: A color change is only able to invalidate if it is noticeable to majority of people at first site.
Menumar- Leopard Esrog: An Esrog with spotted colors is Menumar and is invalid due to it not considered Hadar. The following is the definition of Menumar: Any Esrog that has two different colors such as black and white or other colors which are not the normal color of the Esrog is invalid.
The law of color changes caused by thorns: The color change is only problematic if it occurred on its own with the growth of the Esrog. If however thorns punctured the Esrog and caused brown juice to come out and create red areas and indented areas within the Esrog, nevertheless it remains valid.
Bletlach-Leaf marks: A Blet Lach [leaf marks] is valid even if it protrudes above the skin of the Esrog. The reason for this is because these marks are considered as part of the color of the Esrog as it is common for many Esrogim to carry these marks and it is hence not a great diversion.
What is a Chazazis?
A Chazizis is a scab like protuberance made up of two small blisters. If it only has one blister it is not called a Chazazis and is valid even if it is on the Chotem.
Apparent at first sight: A Chazazis is only problematic if it is casually noticeable when held in one’s hand without deep concentration. One is not required to contemplate and search for blisters [and if he does not see it with a regular look then the Chazazis is valid even if it is on the Chotem]. Similarly a color change is only able to invalidate if it is noticeable to majority of people at first site.
A. The law on the First day of Sukkos:
Within the Chotem: If there is a Chazazis or color change on the top part of the Esrog, called the Chotem, it is Pasul.
What is the Chotem? The Chotem is defined as the area towards the upper half of the Esrog [towards the Pitam] that begins to slope inwards.
Below the Chotem: If there is a Chazazis or color change below the Chotem, then if there is only one Chazazis, or color change, it is kosher as long as it does not cover majority of the Esrog. If there are two or more Chazazis, or color changes, then initially it should not be used. If the two Chazazis are so close to each other that there is no room for another Chazazis to grow between them it is considered like one Chazazis. Likewise if between the two Chazazisim there isn’t the natural color of the Esrog it is all considered one Chazazis. Bedieved or in case no other esrog can be found one may use an Esrog that contains two Chazazis or two color changes below the Chotem if from the beginning of the first Chazazis until the end of the second Chazazis it only covers minority of the circumference of the Esrog’s width or length (i.e. they are on the same side of the Esrog). If however it covers majority of the circumference of the Esrogs width or length (i.e. they are on different sides of the Esrog) it is Pasul according to all opinions.
Peeling off the color change or Chazazis: One may Kasher an Esrog through peeling off an invalidating Chazazis or color change from the esrog in the following method: He is to peel off only the thin green skin of the esrog, as opposed to its white body, thus assuring that nothing is missing from the body of the Esrog. Likewise after it is peeled off its color may not change from the normal Esrog color. If these two conditions are fulfilled the Esrog is now kosher. This may be done even initially to validate an Esrog that has invalidating color changes or Chazazis.
B. Second day in Diaspora:
On the second day of Sukkos in the Diaspora an Esrog with an invalid color change or Chazazis remains invalid just like on the first day. If however no other esrog is available one is to use it without a Bracha.
C. On Chol Hamoed:
One may not use an Esrog with an invalid Chazazis or color change even during Chol Hamoed. If however absolutely no other Esrog is available one may use such an Esrog with a Bracha.
If an Esrog has a color change or blister which is noticeable at first site then if it is on its Chotem it is invalid. If it is below the Chotem it is valid. If there are two or more color changes below the Chotem it is not to be used initially and is invalid even Bedieved if the two Chazazis or color changes take up majority of the circumference of the Esrog.
Problematic Color Changes:
What is the law if one’s Esrog became brownish due to it being used by many people?
The Esrog remains valid, and on the contrary this is its beauty when it becomes browned due to the Mitzvah.
 648/16; 19-20;
 648/26: Chazazis and color changes have the same law regarding all matters. [As by both the invalidation is because they are considered Menumar or spotted.] Thus all the laws explained in Admur regarding a Chazazis are likewise applied to a color change.
Other Opinions: Some opinions rule a Bletlach is defined as a Chazazis and is invalid. [see Four Species p. 53]
 A Blet Lach is a type of Chazazis which is. [ibid]
 Meaning that one can feel with his hand a bump by the leaf area hence proving it is higher than the Esrog skin. [ibid]
 648/22; See Arba Minim p. 193; See Hilchos Daled Minim p. 55 for picture of Chazazis. To note however that the picture there does not show a double blistered Chazazis and hence according to Admur it does not invalidate the Esrog if it does not contain a color change.
 So rules Admur ibid based on M”A 648/22 in name of Mabit
Other Opinions: There are Poskim who rule that even one blister is considered a Chazazis. [See M”B 649/49]
 648/16 and 21
 To suspect for the stringent opinion which invalidates any Esrog with two Chazazis [or color changes].
 The reason for this invalidation is because the two blisters are considered Menumar and such an Esrog is not Hadar. [648/19]
Vetzaruch Iyun Gadol how this is supposed to be measured, as one can always measure from right to left or left to right, and up to down and down to up. Thus depending on how you measure it will always take up minority and majority of the circumference. Hence how is one to measure? It depends if they are on the same side. If they are on the same side which means that they are both viewable simultaneously then it is valid. If they are not viewable simultaneously then they are considered on different sides and are invalid. See Arba Minim p. 183 and p. 186; Hilchos Daled Minim p. 19
 Chasam Sofer on Shas 36a brought in many Poskim. [See Piskeiy Teshuvos 648/17]